The Born-In-Sin doctrine (BIS doctrine) teaches that people are physically born into this world APART from Christ. It further teaches that for one to be in Christ, one must first "accept, believe, repent", etc...

Despite its proponents' vehement denial, the BIS doctrine smells of works-based salvation, for UNLESS one pitches in his share of the deal, he remains NOT in Christ.

In contrast, Christ's creation of the One New Man in Himself, assures our being part of His Body all because of His grace, because we all - Jews and Gentiles alike - are the body of this One New Man that Christ created in Himself PRIOR to His death that reconciled us all to God.

NIV Ephesians 2:

14 For he himself is our peace, who has made the two one and has destroyed the barrier, the dividing wall of hostility,

15 by abolishing in his flesh the law with its commandments and regulations. His purpose was to create in himself one new man out of the two, thus making peace,

16 and in this one body to reconcile both of them to God through the cross, by which he put to death their hostility.

NKJ Romans 5:

10 For if when we were enemies we were reconciled to God through the death of His Son, much more, having been reconciled, we shall be saved by His life.