You are entirely ignorant on this subject and it really shows
God commanded Abraham to be circumcised as part of the Abrahamic covenant, that being 4,000 years ago, not 2,000 years ago. This then continued under the giving of the Mosaic Law, which was about 3,500 years ago. Now, I said you clearly hadn't read Galatians, and based upon your comment, you still clearly haven't. Galatians was written to address Christians who were listening to Judaizers who wanted to put them back under the Law, namely circumcision. Christians aren't under the Mosaic Law (Romans 10:4) and we don't have to follow circumcision. Many Christians in America don't know how to rightly divide, and they want to be under the Law.
Additionally, cutting off a flap of skin is barely comparable to chopping the whole chunk of flesh off! It's like saying removing an appendix is the same as removing a heart.
Now, before you come up with some convoluted reason as to why I'm wrong, READ GALATIANS.