Red Letters

Matthew 5:17-20
“Do not think that I came to abolish the Law or the Prophets…until heaven and earth pass away, not the smallest letter or stroke shall pass away from the law until all is accomplished. Whoever then annuls one of the least of these commandments, and so teaches others, shall be called least in the kingdom of heaven; but whoever keeps and teaches them, he shall be called great in the kingdom of heaven.”

This is a problematic passage, as it upholds firmly even the least of the commandments in the Law and the Prophets (incidentally would that be the one about cooking baby goats in their mother’s milk?). These are commandments completely ignored by modern Christians, whose behavior is based on the clear examples in Acts and the Pauline epistles.
Christ applies the law in its entirety to all people and all time until the end of the world, so it does not seem to allow an easy way out for Peter and Paul and the church which followed them. This paradox is not frequently addressed, given the strength and volume on the other side of the question, but this passage definitely is hard to place in Christian doctrine.

“…unless your righteousness surpasses that of the scribes and Pharisees, you shall not enter the kingdom of heaven.”

Perhaps the key to this and the last passage is the difference between entrance and rank in the kingdom. Law-breakers are said to be “least in the kingdom” while those who do not surpass the Pharisees will not enter the kingdom at all. The Pharisees were as close to keeping all the law - outwardly at least - as anyone, yet would not enter at all.
The Law, as Paul realized, serves to show us our own inadequacy. Christ is upholding the impossible standard, but His sacrifice provides the bridge across the gap left by our infinite shortcomings.