The churches in Asia Minor, even where Paul was a founder, broke with him over the issue of pagan-butchered meat. Abstention from meat was unusual (in some places, meat was only in the diet of the rich, but much of Asia Minor is too mountainous for crops and is devoted to sheep-grazing), drawing attention to Christians and causing trouble with the government because of its implied disrespect to the gods of the state. Pliny's report to Trajan notes that after a crackdown on Christianity, the meat markets were back to normal “where previously they could scarce find buyers” (indicating that his province of Bithynia already had a substantial percentage of Christians). Thus, Paul's position was part and parcel of his policy against causing any trouble with the ruling authorities. The complaint “All Asia has turned against me!” may or may not be from Paul (it is in the Pastorals, whose material is always questionable) but does reflect a general breach between the Pauline churches and the “Johannine” churches of Asia. John may have mellowed in his age, but at first was a firebrand (Jesus nicknamed him and his brother James bani-rgesh “sons of thunder” for asking that an unfriendly town be destroyed by fire from heaven) with more hostility to Rome, and to Paul, than either James the Righteous or Simon Peter. He congratulates the church of Ephesus for turning against “those who call themselves apostles but are no such thing” (Paul claimed to be an apostle directly appointed by Jesus, regardless of whether the disciples approved of him or not). At some point, Paul's friend Timothy was booted out of Ephesus; John took over, probably shortly after his trip to Rome.
Bishops of Ephesus would later be proud to claim both Timothy and John in their lineage, though it was probably not amicable at the time. Ephesus did not, however, exert any supervisory authority over the other churches of Asia, or claim to have the right to. A notable difference between this zone and the others was the absence of any formal line of “successors”; authority among churchmen appears to have been a matter of individual prestige, and seniority. John came to be called Presbyter “the elder” in his later days; some think “John the elder” was a different person from “John the disciple”, but I see it as a natural title for him to acquire when he was not only of advanced biological age, but the most senior surviving Christian. Sometimes later authors would speak of bishop Polycarp of Smyrna as “the successor of John”, but he became so, again, because he lived a long time, eventually becoming the last person to have met any of the 12 disciples (although he cannot have been more than a teenager in John's last days), much as John had become the last of the 12. Earlier, bishop Papias of Hierapolis had been an important leader among the Johannines: Hierapolis was where Phillip ended his life, but Papias put more stress on John, as the one who had lived most recently. In his discussion of writings about Jesus, Papias knows a gospel of Mark identical or similar to what we have, and a “gospel of Matthew” which was rather different (sayings of Jesus only, as contrasted to the narrative style of Mark; and in Hebrew, although variant Greek translations, he says, were available), but notably states that he puts no stock in books at all, preferring the “living tradition” passed down orally.
Polycarp also wrote about available writings, in an epistle to the Phillipians. It is clear that by this time any bad feelings about Paul had evaporated: perhaps Paul's death as a martyr improved his reputation; perhaps many Christians had abandoned the practice of avoiding meat, as Pliny indicates; or perhaps the whole issue had ceased to seem important. In any case, asked to tell the Phillipians what they should read, Polycarp warmly commends the epistles of Paul, from which he quotes (especially Paul's epistle to the Phillipians of course), and also the epistles of Ignatius, of which he says he is enclosing a copy (we wish we had Polycarp's edition of Ignatius), and the preachings of the martyrs Rufus and Zosimus (about which we know nothing). He does not mention gospels, which is curious, but it is clear he wants unity among the Pauline, Johannine, and Antiochene churches. Late in life he traveled to Rome, to discuss with Pope Anicetus some differences in church practice. The early church as described in Acts still attended synagogue on the seventh day of the week, but met separately on the first day (the planetary names of the weekdays, like “Sunday”, were not used, just numbers; but the “first day” came to be called “the Lord's day” as the weekly anniversary of the resurrection); once the Jews refused to allow Christians in the synagogues (after the first Jewish Revolt), most Christians met on the first day only, but some on the seventh day only. Polycarp didn't think this mattered, but Anicetus did (however, this was not even uniform in the West: the 4th century bishop Ambrose of Milan held services on Saturday at home, but on Sunday in Rome, hence the saying “When in Rome, do as the Romans do”). Asia commemorated the Passion at the first full moon of spring, coinciding with the Jewish Passover; but Rome only had special readings on the Sundays before and after the Passover (“Palm” and “Easter” Sundays we would now say), otherwise doing nothing special. Polycarp thought the Passion needed its own dedicated holiday, but Anicetus thought it unwise to celebrate on the same day as the Jews; they had to agree to disagree. When Polycarp went home, he was arrested in an ironic foreshadowing of “blood libel” persecutions of the Jews in medieval times: it was believed that Christians practiced cannibalism (a misunderstanding of the Eucharist), so when a boy disappeared it was said that the Christians had eaten him, and Polycarp was well known to be a Christian. The Romans said to him, “Spare yourself, old man! Denounce the Christians! Say, away with the atheists!” (Christians were called “atheists” because they denied the Roman gods) so Polycarp gestured at the crowd and said “Away with the atheists!” His sarcasm was detected, and he died for it.
At some point the Johannines decided that they did indeed need a written “gospel” of their own. The fourth gospel contains three sorts of material: the “Passion” is a well-preserved 1st-century narrative, by someone well familiar with the geography and customs of the city of Jerusalem during the period (information it would be hard for someone later than the Jewish Revolt and its attendant destruction to obtain); the “Discourses” are speeches purportedly by Jesus, but never matching anything attributed to Jesus in the “Q” material (in the gospels of Matthew and Luke) or “the gospel of Thomas”; the “Signs” are a set of disconnected wonder stories, similar to the “Eggerton gospel” (a manuscript containing an otherwise unknown gospel of this genre) or the “W” material in Luke (the “wonders and women” source, concentrating on faith-healings and redemptions of women; possibly, this and the “We Document” are what Luke the physician actually wrote). We have a small but revelatory fragment from c. 125, earlier than anything from any other gospel, probably not long after Polycarp's epistle with its mysterious failure to mention any gospels (typically, that date is questionable, because in one verse Ignatius is alive and in another his martyrdom is reported; I take it that the epistle was written before Ignatius' death, but some later tamperer has made an interpolation, as happens with annoying frequency in early Christian literature). The fragment gives a scene from the trial before Pilate, with “Passion” text present but “Discourses” text absent: Pilate asks “Are you a king? What is the truth?” whereas, in the canonical book, between “Are you a king?” and “What is the truth?” a speech by Jesus (“My kingdom is not of this world...”) is interpolated (other accounts have Jesus keeping his mouth shut). The editor who stitched these three strands together (and probably created the “Discourses” which, unlike the other two, probably never existed as a stand-alone document) appears also to be the author of “1st John” (2nd and 3rd John are too short for much linguistic analysis) and a follower of Polycarp, some of whose phrasings are used. We would like to know the author of the “Passion”: I cannot make myself believe that the “beloved disciple” was from Galilee (Jerusalem, rather), or a poor fisherman (socially well-connected, rather), or the kind of hothead who wrote Revelation (that, I do believe to be the genuine voice of a semi-literate Galilean fisherman); but neither can I take seriously recent arguments that Mary Magdalene wrote it. An old tradition, hotly disputed by the orthodox, had Cerinthus writing both the gospel of John and the Revelation (I think it impossible that the same author wrote both). Cerinthus taught Ebionite views in Asia Minor in the late 1st century. Irenaeus denounces him as a Gnostic, claims that Polycarp told a story about how John knew him and detested him, and says that 1st John with its denunciation of those who deny that Jesus was a being of flesh-and-blood was specifically written against Cerinthus; but Irenaeus is often wrong (and not seldom seems to be flat-out dishonest) about the views of opponents: Epiphanius, a better source, says the views of Cerinthus were quite the opposite of what Irenaeus accuses him of; Jesus was, as for Ebionites generally, an exalted human, totally flesh-and-blood; Cerinthus taught about a “demiurge” agent of God, but as in Philo or the “gospel of John”, the demiurge is the Logos and good, not evil as among the Gnostics; the Torah is of God, and remains binding; Cerinthus did have a written gospel, but it was in Hebrew.
There were three subsequent additions to the gospel of John, two of them minor: the “woman taken in adultery” story is a popular favorite (the line “Let he that is without sin cast the first stone” is among the most-quoted gospel verses), but did not appear until the 5th century (in one manuscript, spliced into Luke instead of into John); chapter 21 (appearance of the risen Christ in Galilee, to eat some fish) is present in all full manuscripts, from the 3rd century onward, but does not appear to belong, since chapter 20 ends with a “wrap-up” (and chapter 21 casually refers to “the sons of Zebedee” as if we know who they are: the rest of the gospel of John never mentions “Zebedee”). The most important addition, however, is the “Logos hymn” at the beginning. Tatian's epistle to the Greeks c. 150 AD quotes it with the phrase “as it is said” rather than “as it is written” (as for any scriptural quote); he knows it as an oral saying, in the liturgy. Tatian composed the Diatessaron “through four sources”, a translation into Aramaic of Matthew, Mark, Luke, and John folded together: those four gospels existed in roughly, but not exactly, their present forms, and there came to be many variant Diatessaronic texts, as editors “fixed” them to make them match passages in the Greek canonical texts which Tatian's original didn't; the inclusion of the Logos hymn in some, but not all, texts was one of those fixes. Eventually the Peshitta “separated” translation of the gospels supplanted the Diatessaron, which the church collected and burned (we have few surviving copies) because of these embarrassing variations; but the passage in Tatian's epistle clarifies the case of the Logos hymn, that it was not in the gospel text as of the mid-2nd century. All of John 1:1-17, in my view, is an editorial elaboration of the original liturgical hymn, which at first was in a “call and response” form between the presider and the congregation, and was probably the same “hymn addressed to their founder as if to a god” which Pliny's letter to Trajan says the early Asian Christian church service opened with. The gospel would earlier have started with the line “This is the testimony of John” (1:18) where “John” there actually refers to John the Baptist, who relates the first of the “Signs” stories; but perhaps a careless reading of that line caused some readers to attribute the “Signs” book to John the disciple.
Ironically, I do think that the Logos hymn, although not in the first “edition” of the gospel of John, is the section that is most likely to have been actually composed by John. If it was already well established as a liturgy by the time of Pliny, it has to have come from a 1st century leader, and John is the primary candidate. John's view of Jesus as we see in Revelation was much higher than what we find among the Ebionites: to Cerinthus, for example, Jesus was infused with the Logos at the time of baptism, but abandoned at the time of the crucifixion; the author of the Logos hymn sees Jesus as metaphysically identical to the Word of God from the beginning of time to the end, much as Revelation addresses Jesus as “the Alpha and the Omega”; the Logos hymn seems more “sophisticated” than Revelation, drawing on philosophical terminology and using correct grammar, but John lived a long time and had ample opportunity to become better educated than he was when Revelation was composed. Irenaeus is the only source for the claim, which has come to be dogma in some circles, that Revelation was written very late in John's life, during the reign of Domitian; I don't trust Irenaeus for much, and see Revelation much more as a product of youth (Irenaeus may have had a propagandistic motive for denying that Revelation existed during Nero's reign, to avoid any possible implication that Christians really were guilty in the “Great Fire” case). The “Discourses” material, though composed well after John was dead, were at least faithful, in their exaltation of the status of Jesus, to the tradition represented by the Logos hymn. We can see why Cerinthus was reviled, but the “Passion” narrative probably come from him (or through him, if he was not old enough to be the “beloved disciple” himself); much as Theophilus of Antioch detested Marcion's views but respected the texts he had collected, the Johannines did find his book, if not his teachings, to be valuable.
The absence of a central authority in Asia made it possible for unorthodox sects to grow to mass movements, which was not generally the case elsewhere. Marcion's followers, the “Paulicians” (since they thought they were the only ones to understand Paul), outnumbered the orthodox in eastern Asia Minor for many centuries, even though the Antiochenes kept them out of Syria. The Valentinians, a Gnostic group from Egypt with a different evil demiurge, identified with “Adam” the first man, had their largest branch in Asia Minor (though they also had a presence for a while in Italy and Gaul). And the “Montanist” or “Cataphrygian” movement had a spectacular boom-and-bust in the late 2nd to early 3rd century. Montanus, from Lower Phrygia, declared himself a new incarnation of God, the “Paraclete” promised by Jesus, embodying the Holy Spirit in fleshly form; but when a couple of his women disciples (and lovers? it is always hard to tell) began to speak in tongues and prophesy, they too were proclaimed Paracletes and after a while, every Montanist was a Paraclete. Their services were a cross between Pentecostal and Quaker: a leader would be chosen by lot, to read a random passage from scriptures (they had their own books) and extemporize, then others would speak as they felt moved, often in tongues, which someone else would then “interpret”. This kind of thing had been common in the early church too, of course, although Paul doesn't seem to have liked it much. The thoughtful theologian Tertullian had been Montanist in his youth, so we are better informed about them than about many smaller sects.
It was Constantine, of course, who created the Patriarchate of Constantinople to govern this region. Constantine is often accused of creating the Papacy in Rome: this is a residue from the medieval forgery “Donation of Constantine” which told how Constantine at the start of his reign had a fatal disease which the priests of Jupiter said they could cure with a baby-sacrifice ritual, but Constantine couldn't go through with it because the babies' mothers were wailing, so he turned to Pope Sylvester who miraculously cured him, and therefore Constantine moved to the Eastern Empire, building a new capital, and turning over the whole Western Empire to the Pope. Vico, a Renaissance scholar, pointed out how absurdly fictional this all was; it is surprising this text was actually believed for as long as it was. As with some other pseudepigrapha, it started with a couple of genuine documents: a land grant to the Pope of an unused administrative building that became Lateran Palace (for a long time a more important seat than the Vatican), and a grant of privilege to use the tightly-regulated red dye (called “Tyrian purple”, Rome's main source of foreign exchange, though insufficient to balance the outflow of gold coin to pay for silk from the east; therefore Rome always wanted as much as possible exported, and allowed few to use it domestically). These genuine bits read almost as a touch of humor within the “Donation”: the Pope is granted all of Italy, Spain, Gaul, Britain, Africa, Dalmatia, Germania, and an office building, with the right to exercise all imperial powers, to judge in all cases whatsoever, and to wear red shoes.
The facts are that Constantine was very disappointed with Rome, both as a city (not only did he move to a new capital, but even when he visited the west he preferred to reside at Treverum, modern Trier, by the German front, and even when he came to Italy he preferred not to go south of Milan) and as an ecclesiastical hub. During the persecutions of Constantine's predecessor Diocletian, Pope Marcellinus had actually renounced Christianity, the most embarrassing “lapse” ever, and though his father Marcellus Sr. tried to take over, he wasn't universally recognized. By Constantine's time, there was again an agreed Pope, the North African Miltiades (his name was a Latinization, assimilated to militus “soldier”, of Melchiades from Punic for “king” plus a Greek affix for “descended from”). Constantine demanded that he deal with the Donatist schism in North Africa: above all, he wanted a unified Christian church; contrary to some impressions, he didn't actually care what the Council of Nicaea decided about doctrine, just as long as they decided something. But because Miltiades had connections among the contending factions in North Africa, he was rejected as a mediator. Constantine then asked the patriarch of Arles to settle the matter: the mutual recognition brokered by Arles did not last, but it was humiliating to Rome for Arles to be given such a role. Sylvester was Pope when Nicaea was convened, but he wasn't invited: Constantine didn't want to take the time to wait for western representatives. However, bishop of Hosius of Cordova (the papal “vicar” in Spain) happened to be in the east, and was given some deference as standing for the whole western church. Rome did get its way on some important issues: Sunday was decreed as the day for the church to meet; Easter was not to be celebrated on the Jewish Passover but delayed to the following Sunday (the Quartodecimans “14th [of Nisan] faction” in Asia who kept to the old custom were stamped out by force); and while most of the eastern bishops didn't like the teachings of Arius (that Jesus was not co-eternal with God, but a subsequent creation) either, Rome particularly opposed them and was glad to see them rejected at the Council. Unfortunately, members of Constantine's family favored Arianism, and forced some subsequent patriarchs of Constantinople to adopt it; imperial domination of the religious authorities in Constantinople was taken for granted from the start, and the Popes in Rome would take pride that they did not change their line, regardless of what various Emperors said (some Popes were banished, tortured, or killed for refusing to knuckle under).
The jurisdiction of Constantinople was expanded, with some resistance. From the 4th century we have the “Acts of Barnabas” supposedly by his cousin Mark (the author of the gospel), giving a believable account of his missionary journeys (probably good information, though it is certainly not by Mark) ending back home in Cyprus: the propagandistic point was that Cyprus was a first-generation church, and shouldn't have to answer to late-comers like Constantinople. Under the Valentinian and Theodosian dynasties, the Empire was formally divided into West and East, and ecclesiastic jurisdictions changed accordingly: the bishop of Thessalonica, formerly the “vicar” of Rome, was now subordinated (along with all Greece) to Constantinople, and although the Popes protested, they never got Greece back. The Goths were converted to Arianism during a period when it was official in the East, and remained Arians when they spilled over the Roman border in flight from the Huns: Roman authorities did not know how to cope with the situation and made promises they couldn't keep, then tried to assassinate Gothic chiefs; the angry Goths invaded Thrace, killed an Emperor and wiped out much of the army at the battle of Hadrianople, but could not attack Constantinople (Constantine had made a wise strategic choice of the capital site) and tried to enter Greece, which didn't work either, so they came back to Thrace (which never recovered from this double rampage) until troops recalled from the Persian frontier finally pushed them back. They retreated across the West/East divide to Illyria, a major military-recruiting center (Naissus, now Nish in Serbia, was the home-town of Constantine's father Constantius, and the ancestral home of the Justinian family, which would later produce some strong Emperors). The West could not dislodge them, so Illyria except for “Dalmatia” (a broader area than the coastal strip now called that, also including modern Croatia and parts of Austria) was temporarily transferred to eastern jurisdiction. Like many “temporary” arrangements, it was never undone, and the modern border between “Orthodox” Serbs and “Catholic” Croats still roughly follows that “temporary” line.
A major part of Rome's downfall was fighting among Romans. The West wanted that bit of Illyria back, and a power-behind-the-throne (another part of the downfall was the growing tendency to put in weak puppets as nominal Emperors) named Flavius Stilicho (a very revealing name: “Flavius” from his mother's side was an old prestigious family, from which had come Emperors Vespasian, Titus, and Domitian; “Stilicho” from his father, a Vandal) proposed an alliance with king Alaric of the Goths against the East. Alaric re-invaded Thrace (yes, they “raped Thrace thrice”) but Stilicho did not show up, and the Goths realized they were being played for suckers, Stilicho hoping they would wipe themselves out while doing enough damage to the East that he could pick up the pieces. Alaric finally moved into Italy and threatened the city of Rome, seeking some recognition: he never wanted to bring down the Empire, just to be granted some rank within it, and some territory where his people could settle; but imperial officials holed up in Ravenna, refusing to defend Rome, which Alaric finally sacked, with some reluctance (Augustine noted that Alaric recognized churches as sanctuaries, rather unheard-of behavior given the nature of war in those days, especially since Alaric was not even Catholic). He then tried going south, hoping to assemble a fleet and move to Sicily or Africa, but Goths never had much luck with ships. When he died, his successors went back north and established their realm in Gaul and Spain; another branch of Goths would finally take over Italy, until Justinian retook it for the Empire, without much enthusiasm from the Popes or the Italian populace, so that this restoration of partial imperial control in the west soon shrank back to small patches. The Popes won the allegiance of the Franks to Catholicism, and it was to them rather than to the East that they looked for help against the Goths and Lombards. A Gothic king Reccared, his realm reduced to Spain, sought peace and a marital alliance with the Franks, the price being renunciation of the Arian heresy. The Council of Toledo set out the terms for Reccared to be accepted into the good graces of the Catholic church, and this included recitation of the creed. By some unfortunate error, the text of the creed imposed on the Goths said that the Holy Spirit proceeds from the Father “and from the Son”, an addition that did not belong there, and which Constantinople would never accept.