You posted:
“That he committed this act in church is even more henious.”
Why?
Exodus 21:12-14 states “He who strikes a man so that he dies shall surely be put to death. But if he did not lie in wait for him, but God let him fall into his hand, then I will appoint you a place to which he may flee. If, however, a man acts presumptuously toward his neighbor, so as to kill him craftily, you are to take him even from My altar, that he may die.”
God was talking to a specific group of people about a specific instance. You can find justification for anything in the Bible, but it doesn’t mean it was what God intended. Should we murder whomever we please?
God said that vengence was his, did he not?