>>507952307 (OP)Because circumcision was a way to mark the cattle for military in service of protecting the land of Canaan. Instead Christians have a better mark, the mark of the blood of Jesus that covers our sins. That is what that baptism represents, being covered in water/blood which represents the Holy Spirit. Not a little sprinkling of it, but covered in it after one believes on the Gospel. It's how we outwardly confess our faith in Him.
The 4 Gospels, Matthew, Mark Luke and John are all still Old Testament because Jesus' Testament came after his death.
So you can still do circumcision but it has absolutely no meaning whatsoever and is mostly Jewish tradition. So if you like Jews and want to keep their traditions have at it, we don't hate Jews but we aren't Jewish.
[Gal 5:6 KJV] 6 For in Jesus Christ neither circumcision availeth any thing, nor uncircumcision; but faith which worketh by love.