Protestants are fond of saying that Catholics reject "the finished work of Christ" since Catholics reject Salvation by Faith Alone. A popular text they appeal to is John 19:30, which mentions the final words of Jesus on the Cross, "It is finished!" By this, they suggest Christ did everything necessary for our salvation, that He paid everything, all that's left is for us to believe. To deny this, they say, is to deny the Gospel. While at first this might sound convincing, it's an unfortunate and serious distortion of a beautiful text.
The first thing I'd suggest people think about is that Jesus said "It is finished" before He actually died and before He Resurrected. If someone were to push this too far in the wrong way, it would end up saying the Resurrection and even the Death itself wasn't necessary. (Note: Calvinists technically deny the sufficiency of the Cross, they just don't realize it.) Given this, there needs to be a more careful approach to the text.
What many don't know is that there is actually a very good explanation to this text that can be discerned simply by examining the context:
Notice that the focus of this event was not about Jesus paying the full penalty for sin, but rather about fulfilling an Old Testament prophecy. It was when Jesus received the sour wine (vinegar) that He spoke these words, fulfilling the set up from verse 28. In fact, the Greek word for "finished" only appears twice in John, in verse 19:28 and 19:30, under the same verbal form (tetelestai), strongly suggesting the two go together. And the context shows that a few other Old Testament prophecies were also going to be fulfilled (John 19:31-37). So it should really be understood as "It is fulfilled," or more traditionally, "It is Consummated."28 After this, Jesus, knowing that all was now finished, said (to fulfill the Scripture), “I thirst.” 29 A jar full of sour wine stood there, so they put a sponge full of the sour wine on a hyssop branch and held it to his mouth. 30 When Jesus had received the sour wine, he said, “It is finished,” and he bowed his head and gave up his spirit.
The "fulfill" ("consummated") reading also makes better sense of the Greek term used (see how it's used in Luke 18:31 and Acts 13:29). In the 26 verses the word appears in, only twice is it used to refer to payment, and even in these two verse it only refers to paying taxes (Mt 17:24; Rom 13:6) and not some full payment. In virtually every other verse it's used, it means "fulfill" or "conclude". Given this, it is absolutely astonishing the way many Protestants will over-reach with this word to make it suggest a financial transaction of "payment in full" and completely ignore the Biblical evidence available.
This is not to suggest that the "It is Consummated" doesn't have a deeper significance than just saying "this one prophecy was fulfilled," but rather that Christ's death is to be understood as the Old Testament said it would happen. For example, Protestants love to point to Jesus on the Cross saying "My God, why have You abandoned me," and claim this verse proves the Father's wrath was poured out on Jesus. But any alert reader would know Jesus was intoning Psalm 22, which clearly is speaking of David/Jesus being persecuted by enemies and not being rescued (immediately) by God. This same kind of distortion is happening when Protestants quote "It is finished." In the case of "I thirst," the cross-reference given for this is Psalm 69:21, which is a Messianic Psalm talking about how David was persecuted and insulted by his fellow Jews and now how Jesus is persecuted and insulted by the Jews. Nothing to do with taking someone's punishment or the Father's wrath being dumped on them.
Hat tip to this Catholic blogger for his work on this verse.