The God of the Old Testament did what he did because in those days, it was better to die than continue to sin.
1) Comma after because. "In those days" is considered a parenthetical expression, and thus is surrounded by commas. -1
2) What a silly argument. Wouldn't it be better to change your ways than to die?
Jesus' death changed that, both for the future and retroactively I believe.
1) Comma after retroactively. -1
2) How does this compare with God being the same, "Yesterday, today, and tomorrow?"
But yeah.... it's not that he was a murderer.
1) You don't need an ellipse here. -1
2) An ellipse only has three dots, not four. -1
3) "But yeah," is totally unnecessary. -1
4) Yes, yes it is that he was a murderer.
I have faith in an Omnipotent being, and it makes perfect sense that an Omnipotent being would know when and where to distribute death.
Actually, you're misusing the word "omnipotent." -1
Omnipotent means "all-powerful." It doesn't say anything about his intelligence. The word you really want is "omniscient" (all-knowing). And while an omniscient being might know when and where to distribute death, the idea of murdering someone because of their sins (or, in the case of what's actually in the Bible, not being Jewish), goes against another trait of your god, which is "omnibenevolent" (all-loving).
Overall, you only receive a -4 on my grammar scale. Please proofread more.
