Foreskin

For we are the circumcision, which worship God in the spirit, and rejoice in Christ Jesus, and have no confidence in the flesh." - Philippians 3:3

I found out in my walk with God that we may be born in Church, yet not be children of God. Possibly, we can be involved in all areas of church service, yet not be born again. Manifest all the gifts of the Spirit, yet not be in Christ! It reminds me of Samuel who lived in the house of the Lord, serving Eli, consequently, doing work in the house of the Lord, yet "did not yet know the Lord, neither was the word of the Lord yet revealed to him". ( 1 Samuel 3:7)
The phrase 'born again', is one that is easily proclaimed and confessed. But it is beyond that! We begin to understand it when we come to realize what circumcision truly is; no not circumcision of the flesh but of the heart which is of the Spirit.
This higher dimension of circumcision is to be truly born again. This dimension of circumcision is what Apostle Paul called "a seal of the righteousness of faith". - Rom. 4:11
May we truly be renewed in our minds: forget about ourselves, pick up our cross without shame and go to Him outside the camp (this world) and it's devilish philosophy, even ready to die for the Kingdom.