How can one bless a persecutor? How can one love an enemy? How can one forgive, even when the crime is being committed? Where does that come from? It comes from the example of Messiah on the cross. It comes from the Risen One living inside us, and bringing about His dying through us. It comes from character that has been transformed by love for God and neighbor.
And as they were stoning Stephen, he called out, “Lord Jesus, receive my spirit.” And falling to his knees he cried out with a loud voice, “Lord, do not hold this sin against them.” And when he had said this, he fell asleep. Acts 7:59-60 (ESV)