A.T. Robertson Commentary Galatians 3:29

"And if ye are Christ`s, then are ye Abraham`s seed, heirs according to promise." — Galatians 3:29 (ASV)

If ye are Christ's (ε δε υμεις Χριστου). This is the test, not the accident of blood, pride of race or nation, habiliments or environment of dress or family, whether man or woman. Thus one comes to belong to the seed of Abraham and to be an heir according to promise.