The chap I sit next to is quite a committed Christian - church on Sundays, church fundraising, and so on. And he says "God" or "Jesus" far more than I do.
One Christian web site I looked at just now puts it rather well. The third comandment (Ex. 20:7) "forbids us to pronounce the holy Name of God without reverence, and forbids any trivial mention of God in superficial conversation." The verse makes a unique specification in this regard: "Thou shalt not take the name of the Lord thy God in vain;
for the Lord will not hold him guiltless that taketh his name in vain." (Italics mine.)
It is widely held that the original intent was to enforce contracts, which would have been sworn with an oath. I find this persuasive, but limited. Clearly, the ancient Israelites also understood this to mean that one must literally not speak God's four-letter name. There are many Hebrew names for God that you may speak, though none frivolously. And even Hebrew euphemisms for God are not written out except on documents that will be preserved carefully and not mistreated. If even a scrap of paper with a god name on it should become unusable, it must be disposed of in a special place called a
genizah, which is a sort of holding area for such documents. Periodically, the
genizah is emptied and the documents are buried, usually in the grave of some respected scholar when he dies.
Religious Jews are careful even of the
English word "God." They'll substitute a dash for the letter o: "G-d" And when they want to express the sentiment of "thank God," they'll do it in Hebrew by saying
baruch ha shem, which means "blessed be the name." They won't actually
say the name.
It's punctilious to the point of OCD, but that's what I call obeying a commandment.