“Mary, did you know?” Space-time and the Immaculate Conception
"Mary did you know that your baby boy
has come to make you new?
This child that you've delivered will soon deliver you."
It seems that every Christmas season, there is a new formulation of the Catholic objection to these lyrics. It usually goes something like this: the lyrics state that Mary delivers baby Jesus—in the childbirth sense of the word—before Jesus delivers her—in the salvation sense of the word. This, the critics claim, contradicts the doctrine of prevenient grace, as it is because of the future actions of Jesus that Mary receives the grace of her Immaculate Conception and is able to become his mother in the first place. In other words, by the time she delivers Jesus, he has already delivered her. 
While it is understandable, even commendable, to focus on theology in our critique of Christian art and narrative, it is less so when the theology on which the critique stands can be reasonably debated.
I will admit a conflict of interest in that I love this song and would like to defend it. It has brought me to tears and brought me closer to Mary and thus closer to Jesus. For a Catholic who doesn’t usually enjoy religious music unless chant or an organ are involved, that should tell you something.
But I am defending more than a song here. I am defending our proper understanding of time-connectedness, providence, and causality.
Mary the mother of Jesus was immaculately conceived “by the future merits of her son” and in an act of God’s “prevenient grace“. If you don’t think of this too hard you might not raise an eyebrow but you will if you’re one of the nerds who like me likes to geek out on time, space, and causality. Add in the questions of free will and secondary causes and you have the ingredients for a headachy moment of wonder.
Let’s explore 3 possible approaches at time travel and causality:
The linear time/paradox theory
In the linear time understanding, events need to happen before their consequences happen but that’s OK because God can go back in time and make said consequences occur.
Mary was immaculately conceived because of Jesus and Jesus was born because of Mary’s yes*. So either
a. God waits to see if Mary will say yes, then God goes to the past and makes her conception immaculate OR
b. God continues to wait until Christ’s passion, then goes to the past and makes her conception immaculate
Do you see the problem? There are now two possible timelines. In one, Jesus is born to a mother who hasn’t been immaculately conceived and has to undergo the passion to then cause the immaculate conception. In the other, Jesus is not the cause of Mary’s immaculate conception.
There is a third alternative that God makes Mary immaculately conceived before any of this happens. If he does it just in case she says yes , God would have to go back in time to remove that grace if she says no, but God doesn’t make mistakes, so that can’t happen. Even if he does it “because God knows the future” it is the same story with the only difference being that the time-bending happens in the simulation that God runs in his mind, so to speak.
So not only is this kind of a mess, but it requires God to bend the arrow of time into a pretzel and causality no longer works.
* For those who are counting. Mary’s yes IS a cause for the coming of Christ and thus her immaculate conception, albeit a secondary cause and that’s ok.
The multiverse theory
One could think that we live in the one universe of many and that this is the universe where Mary said yes and the plan of salvation was accomplished, but a) humans in every universe would be saved by Christ’s sacrifice anyway and b) multiverse theory is a boring and hand-wavy way to kick the conversational can down the road and we are engaging in serious logic here, so I’ll move on.
The space-time theory
My favorite (and also the correct one).
God, being outside of time and having created time, experiences all moments of time from outside of it. We call the place outside of time eternity.
Space-time is how we physicists understand the, let’s call it container of, the Universe. It is not only 3D space where everything exists, but it is 4D space-time where everything exists and happens. Space-time can be bent, curved, it expands (ask Hubble) and you can make waves in it (ask Ligo) , but that’s a story for another time, suffice it to say that the science we understand supports it.
We observe causality as connected to time. First, the cause happens. Then, the effect happens. This is just because we are not God and are 3-dimensional beings. The space-time theory helps us understand that God experiences time in a different way than we do and thus he experiences causality in the real way causality works which is independently from time.
This is way cooler than just thinking it as God knows the future. God in fact sees and “experiences” ALL moments “simultaneously” for lack of better terms. He sees events not in a progression that unfolds one instant after another but as objects in space-time within creation. The saving plan of God is built into the Universe, not because he merely set it in motion and not because he’s traveling back and forth in time making miracles happen as needed. God creates all moments of time. He creates. Not created in the past at some time t=0 because t=0 if it exists, is just a place in space-time.
Our minds might bend into a pretzel, but God’s doesn’t.
He makes the Universe such that Christ causes Mary to be saved and immaculately conceived years before the Annunciation while also giving Mary the grace to participate in the plan by asking for her permission to conceive. Just as he asks us permission to come into our lives for our own mission and just as he allows us to participate in our salvation.
“For my thoughts are not your thoughts,
nor are your ways my ways, says the Lord."
Isaiah 55:8-9"
So where were we? Oh right…
Mary did you know?
Of course, baby Jesus “has come to make Mary new”! Yes, she has free will, and she needs to say yes to God, but the life, death, and resurrection of Jesus is the primary cause of our salvation and of the immaculate conception of Mary.
And YES, Christ would “soon deliver Mary” and hadn’t yet.
The song asks about Mary’s experience at a moment in time. Mary experiences time as a human being, not as God, so what Mary knew when Jesus was a baby was before his death in her timeline. The event that makes her new, saves her, and saves all of us had not happened yet in that timeline. So this is a perfectly time-appropriate and causality-appropriate question to ask!
Alright, now that I got that off my chest I’ll go pray a rosary, then listen to that song while I enjoy some eggnog.
Merry Christmas!