Unfortunately, there’s no tidy answer to this. The Protoevangelium of James, an apocryphal text written around A.D. 150, tells an elaborate backstory of Mary’s childhood, portraying her as destined for holiness. Of course, this text is not part of sacred Scripture, so it doesn’t offer a reliable answer. It does, however, show that early Christians were interested in this very question.
Perhaps it’s best to focus on what we do know: first of all, that God made Mary free of original sin at the time of her own conception (the Immaculate Conception) in readiness for her role as Christ’s mother. That said, we also believe that Mary was free to reject this role. To quote the Vatican II document Lumen Gentium: “the holy Fathers see [Mary] as used by God not merely in a passive way, but as freely cooperating in the work of human salvation through faith and obedience.”
Your question is a great one to ask ourselves, too: “Why was I, myself, chosen to be [fill in the blank]?” If God has a plan for each of us, then discerning and following that plan – as Mary did – is the best way to live a meaningful life.
Ginny Kubitz Moyer is the author of Mary and Me: Catholic Women Reflect on the Mother of God. You can visit her blog at