"God" is a generic term, and nobody will know who you are talking about. By the use of "god," are you referring to the Muslim deity, the Zoroastrian deity, any one of the numerous Hindu deities, Greek or Roman deities of the past, etc.? There is only one true God (Deut. 6:4; Is. 45:5 7; Ps. 90:2; John 17:3; 1 Cor. 8:4) and we ought to use His Name so that others know of Whom we are talking.
Moshe ben Maimon (otherwise known as Maimonides), a respected Jewish leader in history, wrote:
If because of a slip of the tongue, one mentions G-d's name in vain, he should immediately hurry to praise, glorify and venerate it, so that it will not have been mentioned in vain. What is implied? If he mentions G-d's name, he should say, "Blessed by He for all eternity," "He is great and exceedingly praiseworthy," or the like, so that it will not have been in vain (Mishneh Torah, Laws of Vows 12:11).
In other words, if we say Yahweh, Yahveh, Yah, Yehovah, Jehovah (the Latinized version of the former), or say the letters, Yud-Heh-Vav-Heh, because His Name is holy, in order to show respect and veneration, and in case we accidentally used His Name in vain, it is encouraged that we should say something like, "blessed be His Name." And why should we not?
When Muslims say "Allah" (the word "God" in Arabic), they say nothing afterward; they do not venerate him. However, whenever they say "Muhammad," they immediately say "peace by upon him" afterward because they do venerate him. This is another proof that Muslims do not worship Allah but rather worship Muhammad. If you are in doubt, who do they offer their prayers to? Certainly not Allah. They pray in the name of Muhammad. Muhammad is the Muslim's true god!
How many professing "Christians" have the disgraceful habit of using the word "God" or the Name of the Anointed One, "Jesus," as an expletive or a byword? When you use these as a curse word, you are using the Name of your God in vain. However, this is not the only way in which you can use His Name in vain. When you call Him as a witness to something that is clearly a lie, you use His Name in vain. When you attribute things to Him that He never said or did, you use His name in vain. When you invoke Him in any way, shape, or form that is not honest, trustworthy, true, and with integrity, you use His name in vain. When you talk about Him but do not live according to the precepts He prescribed, you use His name in vain. When you call yourself a disciple of Jesus, an elder of a congregation, or a lover of God while continuing in a willful or secret lifestyle of sin, disobedience, or rebellion, you use His name in vain.
If you are guilty of using Yahweh's Name in vain, repent, and show it the respect and veneration it deserves!