Jesus asked this to stop Saul in his tracks and make him face what he was really doing. Barnes calls the double name "a mode of address that is emphatic" and says the repetition "would fix his attention." Gill sees tenderness in it: Christ knew Saul "as one of his sheep, though straying, and calls him by name." The key word is "me." Saul was attacking the followers of "this way" (Acts 9:2), but Jesus said Saul was persecuting Him. Barnes explains, "Christ and his people are one," and so "to persecute them, therefore, was to persecute him." Matthew Henry adds that before Saul was made a saint, "he was made to see himself a sinner."

Saul answered with a question of his own: "Who art thou, Lord?" (Acts 9:5). Jesus replied, "I am Jesus whom thou persecutest." Saul, "trembling and astonished," then asked, "Lord, what wilt thou have me to do?" and was told to go into the city (Acts 9:6). He rose from the ground unable to see, was led by the hand into Damascus, and "was three days without sight, and neither did eat nor drink" (Acts 9:8-9). Paul later retold this moment twice (Acts 22:7; Acts 26:14), and before Agrippa he added that the voice spoke "in the Hebrew tongue" (Acts 26:14).

Saul had taken part in the great persecution against the church at Jerusalem. He consented to Stephen's death and "made havock of the church," dragging men and women to prison (Acts 8:1, 3). He then asked the high priest for letters to the synagogues of Damascus so he could bring any followers of "this way" bound to Jerusalem (Acts 9:1-2).

The Greek verb for "persecutest" is dioko. Thayer's lexicon gives its first sense as to make to run or flee, to pursue, and then "in any way whatever to harass, trouble, molest one; to persecute." It is in the present tense here, describing what Saul was doing at that very moment.

This question shows how closely the risen Jesus binds Himself to His people. He does not ask, "Why do you persecute my disciples?" but "Why persecutest thou me?" Barnes connects this to Jesus' teaching that what is done to the least of His brethren is done to Him (Matthew 25:40, 45). Heaven was not distant from the suffering church in Jerusalem and Damascus. Jesus counted every blow as His own.

The question also shows His grace. Jesus came to the persecutor himself and called him by name, before Saul had asked for anything. Paul never forgot it. He later wrote that he had been "a blasphemer, and a persecutor, and injurious: but I obtained mercy" (1 Timothy 1:13), and that the churches heard, "he which persecuted us in times past now preacheth the faith which once he destroyed" (Galatians 1:23).