“For neither is circumcision anything, nor uncircumcision, but a new creation.” (Gal. 6:15)
This is the heart of the whole book of Galatians, right here. Because of the cross, religious performance has no value to your soul’s salvation. What matters is a new creation that comes about only by the cross.
If you grasp the cross there’s got to be a holy “sooooo what” with circumcision, or any religious performance you might do.
You could call this holy “soooooo what” a rule. It’s justification by faith alone:
“And those who will walk by this rule, peace and mercy be upon them,
and upon the Israel of God”