OMG is a violation of the 3rd commandment, unless you’re implying Oh My Gosh.
As I tell my kids, I prefer “Oh my goodness”. I try to make it a habit, and I’m less likely to slide (not to mention that ‘Gosh’ is a slang variant or God).
Nonsense, “legalism”. I know God has many names, but OMG isn’t one of them.
Ever heard of YHWH? The Jews came up with this acronym specifically to NOT use the Lord’s name, in a (wrongheaded) belief that to use His name violated the 3rd commandment.