“Sanctifying grace implies a real transformation of the soul. Recall that most of the Protestant Reformers denied that a real transformation takes place. They said God doesn’t actually wipe away our sins. Our souls don’t become spotless and holy in themselves. Instead, they remain corrupted, sinful, full of sin. God merely throws a cloak (of snow over dung) over them and treats them as if they were spotless, knowing all the while that they’re not.
But that isn’t the Catholic view. We believe souls really are cleansed by an infusion of the supernatural life. Paul speaks of us as “a new creation” (2 Cor. 5:17), “created after the likeness of God in true righteousness and holiness” (Eph. 4:24). Of course, we’re still subject to temptations to sin; we still suffer the effects of Adam’s Fall in that sense (what theologians call “concupiscence”); but God removes the guilt from our souls. We may still have a tendency to sin, but God has removed the sins we have, much like a mother might wash the dirt off of a child who has a tendency to get dirty again.
Our souls don’t become something other than souls when God cleanses them and pours his grace into them (what the Bible refers to as “infused” [“poured”] grace, cf. Acts 10:45, Rom. 5:5 Titus 3:5–7); they don’t cease to be what they were before. When grace elevates nature, our intellects are given the new power of faith, something they don’t have at the merely natural level. Our wills are given the new powers of hope and charity, things also absent at the merely natural level.”
Summa Catechetica, "Neque enim quaero intelligere ut credam, sed credo ut intelligam." – St Anselm, "Let your religion be less of a theory, and more of a love affair." -G.K. Chesterton, "I want a laity, not arrogant, not rash in speech, not disputatious, but men and women who know their religion, who enter into it, who know just where they stand, who know what they hold and what they do not, and who know their creed so well that they can give an account of it."- Bl John Henry Newman, Cong. Orat., "Encounter, not confrontation; attraction, not promotion; dialogue, not debate." -cf Pope Francis, “You will not see anyone who is really striving after his advancement who is not given to spiritual reading. And as to him who neglects it, the fact will soon be observed by his progress.” -St Athanasius, "To convert someone, go and take them by the hand and guide them." -St Thomas Aquinas, OP. 1 saint ruins ALL the cynicism in Hell & on Earth. “When we pray we talk to God; when we read God talks to us…All spiritual growth comes from reading and reflection.” -St Isidore of Seville, “Also in some meditations today I earnestly asked our Lord to watch over my compositions that they might do me no harm through the enmity or imprudence of any man or my own; that He would have them as His own and employ or not employ them as He should see fit. And this I believe is heard.” -GM Hopkins, SJ, "Only God knows the good that can come about by reading one good Catholic book." — St. John Bosco, "Why don't you try explaining it to them?" – cf St Peter Canisius, SJ, Doctor of the Church, Doctor of the Catechism, "Already I was coming to appreciate that often apologetics consists of offering theological eye glasses of varying prescriptions to an inquirer. Only one prescription will give him clear sight; all the others will give him at best indistinct sight. What you want him to see—some particular truth of the Faith—will remain fuzzy to him until you come across theological eye glasses that precisely compensate for his particular defect of vision." -Karl Keating, "The more perfectly we know God, the more perfectly we love Him." -St Thomas Aquinas, OP, ST, I-II,67,6 ad 3