Yes, I have no doubt that SAUL thought he was doing the Lord's work. But, he was LOST at that time, unsaved, damned. My main point was that Saul was wrong. He "should have known" that murdering was wrong, but he didn't see it that way until our Lord Jesus opened his eyes. (So to speak :) So, I said "he knew" when I should have said "he should have known". :) IOW, not only was he wrong about Christianity, but he was also wrong about what he thought was Judaism.
Reasonable enough point.
I don't think anybody much in those days "knew" that killing members of a heretical sect was wrong. Look at what goes on among Muslims today in that part of the world.
Yes, with God's patient hammering into our heads, we have finally doped it out and reached the "Duh!" moment, but it took a long time for even some humans to get that idea.
SO yeah, if Paul had had a heart attack instead of a vision on the road to Damascus, I guess he'd be in the warm place now.
BUT, I still want to say that being in the state of sin is not JUST evil everywhere. It's more like everything out of joint, out of sync.
By grace (IMHO) Paul was open to God. God was working on him. How trickily God works ("with the crooked You are wily") to convert us without frying our brains! Paul wanted to do God's will (was 180 degrees out of phase on that ...), and, I think knew somehow that he was doing a lousy job of being a son of the Covenant. Maybe even his desperation at his own inescapable sinfulness contributed to the anger and hostility he felt toward us.
Then, I can see a scrupulous thinker wondering,"Suppose I'm just really, really wrong," or thinking, "My sinfulness is so wretched that only an innocent man could pay the price of it ... uh, wait a minute! Oh. My. God."
I'm suggesting, I guess, that God works slowly and carefully, and that He had His eye on Paul and finally finally got him to take the bait, and rejoicing reeled him in.