What Is My God?

I've been thinking about a common theme in the Old Testament: The Israelites are constantly straying to other gods. The common application to us today is to ask, "Who/what is your god?"
But how should I understand the question? How do I know whether something has become my god, replacing the true God?

The Book of Hosea gives one definition: My god is whatever I trust:

"For their mother hath played the harlot: she that conceived them hath done shamefully: for she said, 'I will go after my lovers, that give me my bread and my water, my wool and my flax, mine oil and my drink.'

"Therefore, behold, I will hedge up thy way with thorns, and make a wall, that she shall not find her paths. And she shall follow after her lovers, but she shall not overtake them; and she shall seek them, but shall not find them: then shall she say, 'I will go and return to my first husband; for then was it better with me than now.'" (Hosea 2:5-7)

Some verses in Isaiah may give a slightly different definition: My god is whatever I credit:

"Surely your turning of things upside down shall be esteemed as the potter’s clay: for shall the work say of him that made it, 'He made me not?' or shall the thing framed say of him that framed it, 'He had no understanding'?" (Isaiah 29:16)

There is also the popular definition: My god is whatever I focus on:

"And thus we see that except the Lord doth chasten his people with many afflictions...they will not remember him. O how foolish...are the children of men; yea, how quick to hearken unto the words of the evil one, and to set their hearts upon the vain things of the world!" (Helaman 12:3-4)

Any additional definitions (with accompanying scriptures) would be appreciated.

Mocking the False Gods
However we define our false god(s), Isaiah has something quite humorous to say about it:

"Then shall it be for a man to burn: for he will take thereof, and warm himself; yea, he kindleth it, and baketh bread; yea, he maketh a god, and worshippeth it; he maketh it a graven image, and falleth down thereto.

"He burneth part thereof in the fire; with part thereof he eateth flesh; he roasteth roast, and is satisfied: yea, he warmeth himself, and saith, 'Aha, I am warm, I have seen the fire': And the residue thereof he maketh a god, even his graven image: he falleth down unto it, and worshippeth it, and prayeth unto it, and saith, 'Deliver me; for thou art my god.'

"And none considereth in his heart, neither is there knowledge nor understanding to say, 'I have burned part of it in the fire; yea, also I have baked bread upon the coals thereof; I have roasted flesh, and eaten it: and shall I make the residue thereof an abomination? shall I fall down to the stock of a tree?'" (Isaiah 44:15-19)

In other words: "Wake up, you fool! The thing you reverence so deeply is the very thing you yourself created. It should be serving you!"

(And some people think that only Elijah knows how to irreverently mock.)

Speaking of Elijah...
There is an interesting difference between what Elijah teaches and what Joshua demanded. Joshua famously demands a choice:

"Choose you this day whom ye will serve; whether the gods which your fathers served that were on the other side of the flood, or the gods of the Amorites, in whose land ye dwell: but as for me and my house, we will serve the LORD." (Joshua 24:15)

Elijah, on the other hand, shows that there is no choice:

"And Elijah came unto all the people, and said, 'How long halt ye between two opinions? if the LORD be God, follow him: but if Baal, then follow him.'" (1 Kings 18:21)

Now that may sound a lot like what Joshua said, but look at how Elijah follows up on his question:

"And they...called on the name of Baal from morning even until noon, saying, 'O Baal, hear us.' But there was no voice, nor any that answered.

"And it came to pass at noon, that Elijah mocked them, and said, 'Cry aloud: for he is a god; either he is talking, or he is pursuing, or he is in a journey, or peradventure he sleepeth, and must be awaked.'

"And it came to pass, when midday was past, and they prophesied until the time of the offering of the evening sacrifice, that there was neither voice, nor any to answer, nor any that regarded.

"And it came to pass...that Elijah the prophet came near, and said, 'LORD God of Abraham, Isaac, and of Israel, let it be known this day that thou art God in Israel, and that I am thy servant, and that I have done all these things at thy word.' Then the fire of the LORD fell, and consumed the burnt sacrifice, and the wood, and the stones, and the dust, and licked up the water that was in the trench.

"And when all the people saw it, they fell on their faces: and they said, 'The LORD, he is the God; the LORD, he is the God.'" (1 Kings 18:26-39, emphasis added)