It is hard to consider that Saul does not realize that he is being addressed by God. With an obvious theophany, he should have known that he is being confronted by the Lord. 1 Possibly there is a measure of rebellion in his question, though it could also be the result of uncertainty on his part.
5 And he said, “Who are you, Lord?” And he said, “I am Jesus, whom you are persecuting.