Does calling someone a "moron" or "idiot" constitute murder?

[John81]

Only God can know if you commit "heart murder"....you can say "idiot" and not be hateful...or you can say "God bless you" and be full of hate and anger and bitterness.

That's true!

[anotherjeff]

Only God can know if you commit "heart murder"....you can say "idiot" and not be hateful...or you can say "God bless you" and be full of hate and anger and bitterness.

I think this is right too and your conscience bears witness. The point is the heart not just the words used.

Which shew the work of the law written in their hearts, their conscience also bearing witness, and their thoughts the mean while accusing or else excusing one another;) (Romans 2:15)

You know because your conscience bugs you, or you try to shut it off and pretend it didn't really bug you that much. But God does indeed know.
Our problem is we create a god that will just overlook our lil ole' self. Which is Idolatry, and one sin made 2 just that easy. Well it really gets worse because once you self justify that sin, then you go on tell yourself a little white lie like, no one besides me and God knows, and God will forgive me.

And Joshua said unto the people, Ye cannot serve the LORD: for he is an holy God; he is a jealous God; he will not forgive your transgressions nor your sins. If ye forsake the LORD, and serve strange gods, then he will turn and do you hurt, and consume you, after that he hath done you good. (Joshua 24:19-20)

For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins, (Hebrews 10:26) (all scripture needs context to help you understand clearly and right now is a good time to read the whole section)

God won't forgive you. He can't, He is perfectly Just too. (Just as in Justice must be paid)

Your sin must be weighed in the balance, and if you are a Christian, God bloodied His Son instead of you, He paid for your little sin with His blood as He cried with a loud voice... (Mr 15:34)

But God commendeth his love toward us, in that, while we were yet sinners, Christ died for us. (Romans 5:8)
For the wages of sin is death; but the gift of God is eternal life through Jesus Christ our Lord. (Romans 6:23)

Sin has an extremely eternally high price. It's remedy is stunningly costly!