The Crux of Christianity
I was watching a PBS special on Dietrich Bonhoeffer and one of the interesting questions that came up was "Does the sermon on the Mount (Matt. 5- 7:27) embody Christianity?"
Bonhoeffer was influenced by a french theologian named Larrere at Union Theological Seminary in NYC. Larrere stressed the importance of the Sermon on the Mount as the essence of the Christian Faith. Because of that he was a pacifist (See Matt.5:39, "...But whosoever slaps you on your right cheek, turn the other to him also.")
Now, I don't agree that the Sermon on the Mount is the 'essence' of the Christian faith. The primary problem with this view is works righteousness. The Sermon on the Mount emphasized a standard of how people are to live if they really wanted to live according to God's law. Furthermore, the Sermon is not a complete picture of salvation. You can't read the Sermon on the Mount and know how you are saved from your sins. In fact, I would argue that the Sermon on the Mount convicts you of how far you are from living according to God's true law.
Furthermore, I would argue that the essence of Christianity is summed up in Paul's letter to the Romans. In Romans 10:9, "If you confess with your mouth Jesus is Lord, and believe in your heart that God raised Him from the dead, you will be saved..."
Christianity isn't about following the law... it's about the fact that we can't follow the law, and are doomed to God's wrath and eternal misery . But, God in His graciousness has condescended to save a wretched sinner such as me through Christ, THEN out of a love for my Savior do I try and follow His commandments.
Finally, you can't get around the supernatural aspect of Paul's statement, "and believer in your heart that God raised Him from the dead," Christianity is not Christianity without the miracle of the resurrection. The Sermon on the Mount is important and should be studied and obeyed, but it is not the essence of Christianity...Christ and who he is...is the essence of Christianity.