For a two word Gospel, I would say: "Repent! Trust!"
Again, this is straight from the Bible (Mark 1:15):
"And saying, The time is fulfilled, and the kingdom of God is at hand: repent ye, and believe the gospel."The Greek word translated "believe" is πιστευετε (pisteuo). This is better translated "trust".
It is when we turn from sin and turn to God (repent) and trust in the atoning death of Jesus that we are saved.