Hi, Jack —
Condensed, eh? You ask a lot. :-)
Protestants are all over the map when it comes to theology so it's hard to make a single statement about what they believe, but since Protestants come out of the Reformation, I'll confine myself to what the Reformers taught about salvation.
- super-summarize it first
- then go into some detail
- then refer you to a web page.
Both sides see salvation as entirely dependent on God's grace, every step of the way, but Catholicism sees salvation as a process involving the cooperation of the believer which actually transforms the believer into a righteous person worthy of Heaven, whereas the Reformers saw salvation as a one-time event involving no cooperation on the part of the believer which makes a believer legally acquitted of his sin, without actually changing him into a righteous person.
The Reformers conceived of salvation as a kind of legal (or forensic) transaction that involves the imputation of Christ's righteousness to the believer. In essence, God declares the sinner righteous, on account of Christ's taking His place in His sacrifice, even though He really isn't.
Luther used the vivid image of a dunghill covered with snow: It looks clean and white, but underneath it's still corrupt. The imputed righteousness remains alien to the believer; he is subjectively pleasing to God, but not objectively pleasing.
In the Catholic view, God's Divine Life, His Grace, heals the individual of their sin and Christ's righteousness is imparted to the believer — this means that the believer is made truly righteous and objectively pleasing to God. We would appeal to verses such as:
Thus the person truly deserves to be saved and is worthy of Heaven. Of course, the process of justification — being made righteous — is all dependent on God's grace, and all flows from the merits of Christ's sacrifice on the Cross, so it is nothing we earn.
There is an additional element to this however.
Protestants (including the Reformers) tend to view salvation as a one-time, once-for-all event. One moment you are a sinner, bound for Hell; the next moment you are justified and bound for Heaven (sometimes irrevocably), and that's that.
In Catholicism (and Orthodoxy), salvation is a process, and we can be justified multiple times in our life. This is evident in Scripture; St. Paul says that Abraham was justified when he believed God (Romans 4:9), and St. James says he was justified when he offered his son (James 2:21).
So we believe that after a wicked man is justified and made righteous — which is strictly based on grace through faith alone — it is possible to grow in righteousness by doing good deeds prompted and enabled by God's grace. Salvation:
- starts at Baptism (where we believe we are justified by grace through faith alone),
- continues through our Earthly life (where we can grow in righteousness and holiness, or even forfeit our righteousness through sin), and
- ends when we are glorified in the Resurrection.
Thus a Catholic can say,
"I have been saved, I am being saved, and I hope to be saved."
An additional question is whether the believer participates in his own salvation.
In Catholicism, God's grace enters the soul and awakens the will, enabling it to cooperate with grace, to come to faith, and so be saved. Thus it is synergistic, a cooperation between God and man (with God as the Initiator, and man always, at every step, dependent on God's grace).
In Reformed traditions, salvation is monergistic: It's completely a unilateral act of God, and man's will does not cooperate in it.
The Catholic view of salvation tends to be more both-and rather than either-or, and organic, meaning that it relies less on the courtroom analogy Luther emphasized, and more on the examples in nature that Jesus tended to use: (crops, families, trees, vines, life/death dichotomy, etc.).
For more details, Wikipedia has a good article on this:
[PDF: A John DiMascio recommenation]