Upvote:-1
Baptism is considered by the Catholic Church to be a cleansing not only of personal sin ("past actions", as you put it) but also original sin. Original sin, confusingly, is not "really" a sin. That is, it's not a sin in the same sense that adultery (for example) is a sin. It is a change in human nature that was brought on by the first sin, which has effects persisting for all humans:
Although it is proper to each individual, original sin does not have the character of a personal fault in any of Adam's descendants. It is a deprivation of original holiness and justice, but human nature has not been totally corrupted: it is wounded in the natural powers proper to it, subject to ignorance, suffering and the dominion of death, and inclined to sinβan inclination to evil that is called "concupiscence". Baptism, by imparting the life of Christ's grace, erases original sin and turns a man back towards God, but the consequences for nature, weakened and inclined to evil, persist in man and summon him to spiritual battle.
(Catechism of the Catholic Church paragraph 405)
Children are not seen as sinful at birth. Indeed, since sin is the result of a voluntary action, word, or thought, it is not possible for a child to sin until they are (as the saying goes) "old enough to know better". (The Church generally takes this to be about six or seven years old.)
Baptism, among other things, allows a person to be justified before God, and to receive again the strength to pursue holiness which original sin deprives us of. It also cleanses us of any previous personal sins we've committed.
Adam and Eve are the only ones responsible for their actions (and thus the passage from Deuteronomy applies to them, in that we are not condemned for what they did); but on the other hand, their actions changed human nature in such a way that it is, generally speaking, impossible for us not to be sinful to some extent. Thus, it is in a sense because of their actions that we can be sinful; but any condemnation that comes on us is because of our actual choices, not because of that first sin.