There's evidence of 'factionalism' even among the earliest Christians (in the 1st century) on this very issue. In many cases, much of the tension arose between Jewish and Gentile Christians. But not necessarily. One of the narratives in the New Testament itself that addresses dietary issues (and some of the Christian innovations regarding them) is found in the 10th chapter of the Acts of the Apostles:

Peter went up on the roof to pray. 10 He became hungry and wanted something to eat; and while it was being prepared, he fell into a trance. 11 He saw the heaven opened and something like a large sheet coming down, being lowered to the ground by its four corners. 12 In it were all kinds of four-footed creatures and reptiles and birds of the air. 13 Then he heard a voice saying, "Get up, Peter; kill and eat." 14 But Peter said, "By no means, Lord; for I have never eaten anything that is profane or unclean." 15 The voice said to him again, a second time, "What God has made clean, you must not call profane."

This is almost certainly more representative of the so-called "supersessionist" branch, which prioritized the coming/sacrifice of Christ and its transformative effects over observance of Jewish law.

We can see another narrative that addresses kosher/dietary things, just a few chapters later (in Acts 15). Described here is a "council" in Jerusalem, with many the most important Christian figures present: James, Peter, Paul. In the end, these figures produce a letter which is then sent to Gentiles churches, advising that Gentiles should "abstain . . . from things polluted by idols and from fornication and from whatever has been strangled and from blood." This list is virtually identical to that in Leviticus 17-18: prohibiting meat offered to idols (17.8-9), ingestion of blood (17.10-12) and improperly slaughtered animals (17.15).

I've written about this in more detail here - but just to pick out one little section:

there's no real indication from [the council related in Acts 15] that Paul and the Jerusalem church get along anything other than splendidly ("our dear friend" Paul, etc.) . . . Yet the letter that they then send back with Paul (to Antioch, Syria, Cilicia) seems to have "agreements" which, elsewhere, are quite opposed by Paul. While - for the sake of space - skipping over some nuances here, consider Paul's blanket statement in 1 Cor 10:25-26:

Eat anything that is sold in the meat market without asking questions for conscience’s sake; "for the earth is the Lord's, and all it contains"

Ultimately, as the Christian church became a majority Gentile church, the supersessionist 'faction' won out - evidence of which is certainly found in the accounts of Acts themselves (which, as a whole, is a highly fictionalized [quasi-]'history').

It's absolutely fascinating to look at early Islam's relationship with all this. There's some evidence that some of the influence of some of the more primitive Jewish-oriented Christian sects survived, and may have still been around to have influenced Islam (that could be its own thread). But in any case, it all fits in with Islam's portrait of a Christianity which - though still founded by figures that were truly divinely inspired, and worth of reverence - had gone too far in its rejection of the laws and theology of its 'mother' traditions, introducing heretical innovations.

Early Christian's were almost entirely Jewish (as was Jesus himself) and the early Christian "church" considered itself the next step in Judaism. However, many Jews rejected this notion and in many cases persecuted early Christians (see the conversion of Saul to Paul). This did not keep Christianity from spreading to the non-Jewish populations of the Mediterranean.

The aforementioned Paul then wrote many letters to these communities in which there were some serious issues of dietary restrictions and male circumcision were very divisive topics between Jewish and Gentile Christians. In what I believe to be a nice political move, it is decided that there should be no pressure for Christians to be circumcised or to have restrictions on food (the once restriction that I remember at all is to not eat of food offered in sacrifice to idols i.e. Roman or other "gods").

This is just one example of the inclusiveness of the early Christian Church. A major part of the "success" of Christianity is/was it's adaptability.

Christianity does have dietary restrictions: Mardi Gras (Shrove Tuesday / Pancake Day) precedes fasting in Lent and the tradition of not eating fish on Friday are both examples of this.

Edit: incorrect "not".