Why is Jesus Circumcised and not the rest of the christians ?

[Rev. Rye]

Here's how I understand it (note: this will include a mixture of Watsonian and Doylist explanations):

In Early Christianity, there was a lot of controversy about whether or not, as an offshoot of Judaism, Christianity should keep Jewish customs or not. Eventually, the non-Judaisers won out. Sometimes, this happened because Peter had a vision (like the one in Acts 10-11 where God convinced Peter to eat unclean animals) that meant that the Christians no longer needed to be beholden to the old ways, presumably because crucifixion. Eventually, this led to the issue of circumcision. This proved a contentious issue, not just because, well, cutting off your foreskin is painful, but also because, due to the influence of the Greeks and Romans, public bathing and nude exercise became common, and, to them, the sight of a foreskin-free penis was just evidence of a cruel and barbaric act (some argue it technically is, some disagree, and I will not weigh in on the issue here.) The point is, due likely to the influence of the colonizers, it would eventually be deemed unnecessary around 50 AD, and Peter himself would talk about it in Acts 15; Paul would eventually go into further detail about the practice in the Epistles.