Catechism of the Catholic Church:
410 After his fall, man was not abandoned by God. On the contrary, God calls him and in a mysterious way heralds the coming victory over evil and his restoration from his fall.304 This passage in Genesis is called the Protoevangelium (“first gospel”): the first announcement of the Messiah and Redeemer, of a battle between the serpent and the Woman, and of the final victory of a descendant of hers.
411 The Christian tradition sees in this passage an announcement of the “New Adam” who, because he “became obedient unto death, even death on a cross”, makes amends superabundantly for the disobedience, of Adam.305 Furthermore many Fathers and Doctors of the Church have seen the woman announced in the “Proto-evangelium” as Mary, the mother of Christ, the “new Eve”. Mary benefited first of all and uniquely from Christ’s victory over sin: she was preserved from all stain of original sin and by a special grace of God committed no sin of any kind during her whole earthly life.306
412 But why did God not prevent the first man from sinning? St. Leo the Great responds, "Christ’s inexpressible grace gave us blessings better than those the demon’s envy had taken away."307 and St. Thomas Aquinas wrote, "There is nothing to prevent human nature’s being raised up to something greater, even after sin; God permits evil in order to draw forth some greater good. Thus St. Paul says, ‘Where sin increased, grace abounded all the more’; and the Exsultet sings, ‘O happy fault,. . . which gained for us so great a Redeemer!’"308
The catechism is sort of confusing. Though it is clear about God’s purpose, it only makes sense if you forget the part about Him being omniscient.
Once you ask the question "why did God not prevent the first man from sinning? " you are attaching importance to a sequence of events (from being sinless to committing a sin), something that is supposedly irrelevant to God who “transcends” time.
As to “After his fall, man was not abandoned by God”, just implying the before and after means that God experienced man before the fall and after, therefore placing Him within a temporal frame.
If we accept that God is not subject to time, why does the catechism rely on language that implies that time is important to God in regards to relationship with us? Saying “God permits evil in order to draw forth some greater good.” when you have an omniscient and omnipotent God just means He
chose to set up parameters where innocents would have to suffer horribly for the “greater good”. Even if you take into account that these poor people might be rewarded in Heaven, it doesn’t change the fact that God set it up that way when, as an omnipotent being, He didn’t
have to.
And if Jesus’ coming makes amends for man’s disobedience, it implies that God sent Jesus to fix something, something that wouldn’t have needed fixing unless God wanted it that way in the first place.
If God is supposed to have emotional characteristics like love and forgiveness and mercy, then attributing to Him characteristics that make those qualities impossible seem implausible.
And how can He have created us to be loved and for us to love Him if He knew some of us were doomed to Hell from the start? Wouldn’t that mean He actually created
some of us to be loved and to love Him and others just to be used as examples of what not to do?