Actually there was a huge debate among early Christians whether circumcision was still required because Jesus never spoke on the issue (or if he did, there was no verifiable record of it).

To crudely summarize:

The earliest Christians were primarily Jews, so they were already circumcized as required by Judaism so it was a non-issue. However unlike Judaism where you’re almost always born into the religion, Christianity actively encourages adult conversion, so as more non-Jews (e.g. Greeks) began to identify as Christians, the circumcision issue became a conundrum. Some felt Christianity was a branch of Judaism and as such Jewish practices like circumcision were still required, whereas others objected because they saw Christianity as a new approach to Judaism, or even as a separate religion altogether (circumcision specifically was hotly debated due to such issues as adult circumcision being more, shall we say, unappealing than infant circumcision, plus getting circumcized would “out” non-Jews in nude spaces like bath houses, which was at best awkward and at worst deadly).

The earliest followers of Jesus thought Jesus was going to return in their lifetimes, so these types of issues were not discussed (or at least not resolved) by the original founders and proselytizers (researchers have determined the Gospels weren’t even composed until well after everyone involved was dead), but as generations passed it became clear that the Second Coming actually may not happen anytime soon, so practical issues of “how to establish a new religion (is it even a new religion or just a Jewish sect???)” turned into gigantic internal debates for the community. That’s what much of the New Testament is: letters back and forth trying to interpret the words of Jesus to resolve doctrinal conflict. In other words, the New Testament is basically four different versions of the story of Jesus (Mark, Matthew and Luke which were based on Mark and a lost “Gospel X”, and John), followed by a curated back-and-forth commentary section debating issues of the day such as circumcision and women’s role in the church, and controversially capped off by the (theorized) hallucinations of a hermit tripping balls off donated moldy bread.

The history of the New Testament (how it was written and later compiled, early texts that were lost or discarded, and all the doctrinal conflicts that boiled over into variously incidents of geopolitical chaos) is fascinating and seriously worth exploring.