What does that even mean? People say "oh God" or "oh my God" or any of a zillion permutations and mincings of Jesus's name as an exclamation, some more blasphemous than others, all day long. Wikipedia isn't particularly helpful; according to it,
Some have interpreted the commandment to be against perjury,[5] since invoking God’s name in an oath was considered a guarantee of the truth of a statement or promise. Other scholars believe the original intent was to prohibit using the name in the magical practice of conjuration.[6]Old Testament passages also refer to God’s name being profaned by hypocritical behavior of people and false representation of God’s words or character.[7] Many scholars also believe the commandment applies to the casual use of God’s name in interjections and curses (blasphemy).
The object of the command "thou shalt not take in vain" is את־שם־יהוה אלהיך at-shem-YHWH elohik "this-same name of YHWH, thy elohim", making explicit that the commandment is against the misuse of the proper name Yahweh specifically.
The sense that concerns me is that of false representation. In answering yahoos on certain doctrinal topics, I was in danger of falling into a habit of "God told me [x] is OK"... harmless enough in jest but inappropriate in the context I was bandying it. So I repent, and guarding my thoughts more carefully there.
In praying and meditating on this I realized - God occasionally nudges me in certain directions but He is in fact infuriatingly evasive when it comes down to questions of what is the right-thinking, i.e. God-led, position for most values of [x].
Not "Biblical" position because I've searched my soul and prayed on this and the Bible taken as a whole disputes its very own authority. And not "orthodox" because legalism has continually co-opted orthodoxy. -Which touches on Isaiah 29:13, regarding "merely human rules", something else that's been bothering me lately.
And not "all values of [x]". It's a decided leap, one which should be terrifying if you think about it all critically, from "the God of my understanding approves same-sex marriage" to "God revealed to me, directly and personally, that there's room for same-sex couples under the banner of sacramental marriage". (Setting aside for now the fact that marriage is not a "sacrament" per se in Protestantism.)
So anyway, that's the one "God told me" in which I feel no sense of disrespect or blasphemy: He really is totally OK with me officiating same-sex weddings because He doesn't condemn homosexuality in the first place. There's an argument from nature that arrives at the same conclusion, but that's not where I'm coming from today. Why no clear divine policy revelation on, say, abortion or recreational MJ, I don't know.