What do you think Eph 2:1-5 means? To me, it says that the natural man has nothing to do with God regenerating him, because he was "DEAD (spiritually ) in sins" when God regenerated him. He had no ability to respond to spiritual things, such as, repenting of a spiritual law that he could not discern., confess, accept,believe etc. These responses come only from the disobedient child of God, who has already been regenerated. The men that were converted were regenerated children of god. The Jews that were accused of consenting to Jesus's death were PRICKED in their heart. The natural man, who has no guilt of spiritual wrong doing, cannot be pricked in his heart. The people who stoned Steven to death were CUT to the heart and did not ask for forgiveness. So, your answer is NO, the natural man can not be converted. Conversion comes after you have been regenerated.