See the part you’re missing is that many saints have said that unbaptized infants ARE AT FAULT for refusing grace, because GOD CAN SEE THE FUTURE where they reject His grace. There, IN HIS INFINITE MERCY, He allows these babies to die unbaptized, where they go to Limbo. Had they grown up, they’d be damned.
God knows all, sees all, predicts all, plans all, orders all, controls all. Stop trying to understand God. He’s infinitely loving and infinitely merciful with EVERY human being He creates. There is no person that gets screwed. There’s no person than can claim unfairness.
On the contrary, all those in hell will despair for the rest of eternity that they rejected God's innumerable mercies. And those in Limbo will not despair but glorify God (whom they cannot see) for not being damned. And those in heaven will both glorify and worship and adore God fully.
Quote some of those alleged passages from Saints. Let's see them. I've not looked at that before.
But such a Theory has its own Problems: (1) if that's the case, that God foreknew some souls were going to be damned and thus took their lives in infancy, why don't all the damned or at least many more of them die in infancy and go at least to limbo? (2) why do some grow to adulthood and then be damned, while others, who according to this Theory would infallibly be damned if they just grew up and lived long enough, are saved from damnation?
I'm not even saying it's a False Theory. I'm just saying every Theological Explanation/Theory has issues. It's unresolved. Differences of opinion are permitted. Fr. Ludwig Ott's text shows the state of the Question in the 1950s, pre-Vatican II. I just want to add one thing to that - I do think there is a Biblical Example, from Divine Revelation i.e. of Sanctification in the Womb. Namely, St. John the Baptist, through Our Lady, Mediatrix of All Graces, when St. Elizabeth basically prayed the Rosary to Her, in Luke 1:28-48, as St. Gabriel had first begun to do. Now, when they did this, the Holy Spirit fell upon John in the Womb, as Saint Gabriel had prophesied (Luke 1:15), showing Prayers like the Rosary can indeed cause the Holy Spirit, and thus the Grace of Baptism, to fall upon infants even in their mother's womb. This is what some Catholic Theologians have called vicarious baptism of desire, the desire of the parents supplying for the child, just like the faith of the parents suffices or supplies for the faith of the child even in ordinary Sacramental Baptism.
Contrary to erroneous rigorists, God wants us to love, hope and pray, as Saint Padre Pio, one of the Greatest Saints of recent times, who bore the Stigmata and said like 30 to 40 Rosaries (150 to 200 Decades) a day told us to do. There is Biblical Precedent, then, for the belief that Praying the Rosary can cause Children, even in their Mother's Womb, to be filled with the Holy Spirit before they die. It is a deeply interesting and fascinating question imo.
Lord have Mercy on us all.