Answer
I've got an
answer online to a very similar question that someone recently asked. Check that out and see if it answers some of your questions. (The short answer is that while Christ did not spend an infinite amount of time on the cross, his punishment was infinite in intensity, or degree. Because it was infinite in intensity, it did not need to last an infinite length of time, or for all eternity, in order to pay the penalty of eternal damnation.)
The doctrine of purgatory (which isn't addressed in the answer linked above) would not solve your dilemma because it deals with temporal suffering, not with one's righteous standing before God. As I understand Roman Catholic doctrine, the sins for which believers suffer in purgatory are not thereby pardoned. Rather, purgatory is where believers suffer for venial sins that have already been pardoned and covered by Christ's blood. In other words, Christ died for the same sins for which believers suffer in purgatory. That being the case, the extent or value of Christ's atonement is largely irrelevant to the suffering that believers are said to undergo in purgatory.
Answer by Ra McLaughlin
Ra McLaughlin is Vice President of Finance and Administration at Third Millennium Ministries.