What does Matthew 18:22 mean?

Peter has asked Jesus a question about forgiving someone who sins against you. Apparently, Judaism required you to forgive the same person three times for the same offense. Peter, perhaps thinking he is being generous, asks Jesus if he should forgive someone who sins against him up to seven times. Jesus says no. Instead, you must be prepared for effectively unlimited forgiveness.

The only scholarly debate over this verse is irrelevant to how these words are meant to be applied. It can be argued that the Greek construction here means "seventy and seven," meaning seventy-seven times. However, it can also be construed to mean something like "70 times 7 times," meaning 490.

It's possible that Jesus, in naming the number 77, is playing off the words of boastful Lamech in Genesis 4:24. Lamech was talking about revenge against those who might harm him for killing a man. God had promised that Cain would be avenged seven times if anyone killed him. Lamech said to his wives, "If Cain's revenge is sevenfold, then Lamech's is seventy-sevenfold."

Fortunately, nuances of Greek grammar don't impact the main point being made. Here, and in the parable to follow, Jesus means that believers in Him should forgive and keep on forgiving without any plan to stop.