After being the sole survivor of a gangland style drugstore robbery. A charismatic youth pastor retires and plots to kill the ones who left him for dead.

Too many words here. Remember, less is more with log lines. Try this out... (1) After surviving a gang style attack, a youth pastor goes for the kill OR (2) After surviving a gang style attack, a youth pastor has revenge in mind, refusing to leave vengeance to God.
All the best.

This is very strong. However, I think the youth pastor taking revenge for the ones that didn't survive might be interesting as well. Could create an interesting moral dilemma for the story.