God has a name. And it isn't "God." "God" is a title, like "Mister" or "President."
If someone says, "Oh, God!" he's not "taking the name of the Lord in vain" (Ex. 20:7) because he hasn't used a name.
God's name is יהוה . That's probably pronounced "Yahweh." It is NOT pronounced "Jehovah." יהוה is probably a form of the Hebrew verb היה which means "to be." When God spoke to Moses out of the burning bush, and Moses asked him what his name was, God said (Ex. 3:14),
("I am who I am"). The word (the name) יהוה means (approximately) "The one who is." It's an interesting name for a god.
Everywhere in the Old Testament (your English translation) that you see "THE LORD" (small caps) is a mistranslation (actually a non-translation) of God's name.
The use of "THE LORD" in place of the actual name of God began centuries ago with the Jews (it was during the Sixth Century BCE). They would read the Bible aloud in the synagogues, and when they came to the name of God, they wouldn't pronounce it; they would say "Adonai" (lord) instead. Or they say "hashem" ("the name").
And modern-day Jews won't even WRITE the name they usually substitute הי instead.
And where the Bible says "Lord Yahweh" (adonai Yahweh), as it does in Isaiah 61:1, the Jews read it as "Adonai Eloheinu" (which means "the Lord our God"); otherwise, they'd have to say "Adonai Adonai."
Think about it: How can you "call upon the name of the Lord" (Gen. 4:26) when you don't actually KNOW the Lord's name? Your response is (or should be), "Okay, I'll call upon the name of the Lord. But first you have to tell me: What IS the name of the Lord?" The proper translation of Gen. 4:26 is "Call upon the name [of] Yahweh." This may also be the proper translation/interpretation of Romans 10:13.
You are a spiritual entity, with an eternal existence. You have a name. The angels and the demons are spiritual entities, with an eternal existence. THEY have names. God is a spiritual entity, with an eternal existence; he too has a name.