When I was a Protestant and heard Catholics talking about the "Immaculate Conception," I assumed they were referring to how Jesus was conceived. You know, without sex. I assumed Catholics viewed sex as dirty and since Mary got pregnant WITHOUT HAVING SEX, I thought Jesus' conception was The Immaculate Conception.
Welp. I was wrong.
First of all, the Immaculate Conception refers to Mary's conception and secondly, it isn't referring to the act of sex at all.
The Immaculate Conception refers to the sanctification of Mary's soul at the moment of its creation, at the moment she was conceived.
In other words, Catholics believe that as preparation for the special role Mary would play in bearing the Son of God in her very womb, God granted her a unique grace by preserving her from the stain of Original Sin before it had a chance to blemish her soul. To understand why this was necessary, it's important to understand what Catholics believe about Original Sin. When Catholics talk about Original Sin they're either referring to the sin that Adam & Eve committed in the garden of Eden OR the hereditary stain of sin passed down to us.
When Catholics celebrate the feast of the Immaculate Conception we are celebrating the extraordinary abundance of grace that God gave Mary at the moment of her conception, preserving her soul from the hereditary stain of Original Sin.
Perhaps an easier way to understand this is that while you and I are redeemed after we are born, Mary was redeemed before she was born. Like us, she needed a Savior. God simply chose to save her at an earlier point in her life than the rest of us. This pre-birth redemption of Mary, so to speak, is what we call The Immaculate Conception.
To be honest, when I was a Protestant, all these Marian doctrines confused me. And even after I became Catholic I struggled for a long time with the doctrine of the Immaculate Conception. Why was it so important that Mary be preserved from the stain of Original Sin? Why did Catholics make such a fuss about a woman who was "just" Jesus' Mother? To me, it always seemed that venerating Mary somehow detracted from the centrality of Christ.
It has taken me awhile to understand that Mary always brings us to Jesus. I'm not supposed to try and understand her apart from Him. In the end, all the Marian doctrines are really ALL ABOUT JESUS.
In fact, I realized it was a mistake to get all caught up in literalistic questions about Mary, demanding exact chapter and verse in the Bible. The thing is? The earliest church fathers were writing about Mary's purity before the Bible was even compiled. Whoa.
As St. Hippolytus (170-235 AD) wrote: Mary was a "tabernacle exempt from defilement and corruption."
St. Proclus (died circa 447 AD): "She was formed without any stain."
St. Ambrose (340-397): "A virgin immune through grace from every stain of sin."
St. Augustine (354-430): all the just have known of sin "except the Holy Virgin Mary, of whom, for the honour of the Lord, I will have no question whatever where sin is concerned."
Stunner: Catholics have been writing about Mary's purity from the earliest years of Christianity. So, if the earliest Christians believed this--even if it wasn't dogmatically defined until much later--why was I so hasty to discount it? Did I really believe that the best and most faithful witnesses to Christianity only appeared on the scene right around the time of Billy Graham? Or maybe, if we were reeeally reaching back, the Puritans?
Ultimately it came down to an issue of trust: could I trust that the Holy Spirit had led the early church? Wouldn't it be more prudent of me to rest on the hard work and prayer of those saints who had gone before instead of saddling myself with the Herculean task of figuring it all out for myself?
I finally rested in believing that it's enough for me to agree with what the Church teaches--agreeing that the flesh from which the spotless Son of God was formed should be immaculate, too.
And so, like the Angel Gabriel I hail her as "FULL of grace" and answer "YES" to God just like she did.
With deep gratitude for saints' quotes and doctrinal explanation from NewAdvent.org and to Devin Rose whose book "If Protestantism is True" helped me better understand Marian doctrines from a former Protestant's perspective. Also, to Mark Shea and his book: "Mary, Mother of the Son: modern myths and ancient truth". Lastly, my deepest gratitude to Scott & Kimberly Hahn whose book "Rome Sweet Home" was the first book I read that helped me in my journey home to Catholicism.
Other articles I've written about Mary: