Christ’s death delivered from sin. It’s less often recognized that Jesus’ death also glorifies; by His suffering, He brings “many sons to glory” (Hebrews 2:10).
Thomas makes a place for “glorification” as an effect of Christ’s death largely by his attention to the liberation of the saints from Abraham’s bosom or the limbus patrum. Explaining how Christ’s “descent into hell” delivered the “holy fathers” (ST III, 52, 5), Thomas distinguishes between the debt incurred by personal sin and the debt incurred by “the sin of the whole human race, which each one in his origin contracts from our first parent.” The penalty for original sin is death but also “exclusion from glory, as is evident in Genesis 2 and 3: because God cast out man from paradise after sin, having beforehand threatened him with death.” Under the Old Law, “the approach to the life of glory was not opened,” because of “our first parent’s sin.” Christ open the way and thus not only “freed [them] from penal sufferings” but “bestowed something upon them as to their attaining glory.”
It’s possible to affirm that Christ’s passion and death brings sons to glory without positing the limbus patrum. But it sure helps. Perhaps Protestants, in rejecting all medieval notions of limbo made it more difficult to see that glorification is an effect of the atonement.