The Conversion of Saul

And falling to the ground he heard a voice saying to him, "Saul, Saul, why are you persecuting Me?" And he said, "Who are You, Lord?" And He said, "I am Jesus, whom you are persecuting. But rise and enter the city, and you will be told what you are to do."
ACTS 9:4-6
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The Conversion of Saul
The Master here is great, and He produces a great student, Paul, the only one who heard this [sermon] and thereafter became our teacher, who still teaches us today. For Christ here is saying: "Did you hear that, Paul? The whole world is wavering in darkness and error and does not know Me. But you are to call them and lead them from darkness into light, from the devil's kingdom into the kingdom of God, from death to life." "Yes, [but] how?" [Paul asks.] "By what means am I to accomplish this?" "Through the Word, which you, Paul, have now heard from Me in this sermon, namely, that you should preach repentance and the forgiveness of sins in My name. And whoever believes in Me (that I am the true Son of God) is righteous before God and will receive eternal life."

From Sermon on the Conversion of St. Paul (Luther's Works 58:381)