A. It’s not that obvious; there are people who believe only in one God and that there are no other gods. B. What does “someone who thinks there is something real to them” mean? That they are effective or important?
If someone believes in God and even believes He gave the Torah, but just doesn’t accept it because he prefers to believe in other gods—is that not okay?

This discussion is bizarre. Do you think there is anyone who denies the existence of physical idols used for idol worship, or heavenly bodies, or Asherah trees? The question whether there is anything real to them—that is, whether these are actually gods with power and worthy of worship—is a different question. Some of the medieval authorities held that yes, there are other sources of power besides the Holy One, blessed be He, and it is only forbidden to worship them. Maimonides and those who follow his view held that there is nothing there at all. Nonsense. And I, the insignificant one, agree with that too.

I didn’t say people deny the existence of physical idols that people used to worship. Rather, as you said, whether there are spiritual sources of power, additional gods besides the Holy One, blessed be He, that actually exist—after all, you yourself hold that they don’t exist and that there’s nothing to them. Maimonides, by the way, also doesn’t believe in demons or spirits, and from what I understand, neither do you.
So some hold yes and some hold no. The question whether they are gods with power that are worthy of worship really is a different and interesting question. The answer depends on the person: if you accept the Torah, then it is forbidden to worship them. If you do not accept the Torah and its commandments, then you can believe in other gods, and there are indeed people who believe in other gods even while also recognizing God.

Okay, I don’t understand what this discussion is about. For example, what were you trying to prove from planting or setting up an Asherah beside the altar? To prove that Asherah trees exist in the world?

No, it’s just that Judaism presents belief in one God, and it’s interesting to know that gods like Asherah are mentioned in it, or that the first commandment instructs us not to believe in other gods, which implies that they exist but that one should not believe in or worship them. Even though, again, you say you don’t believe in demons or spirits or, as you described it, sources of power besides God. But it seems that in the Torah there are hints that it does recognize this. The first commandment is one example of that. Asherah may be a less good example because that’s only about idols and not spiritual gods, but it seems the Torah recognizes the spiritual gods too. So this discussion also shows that the Jewish religion is not exactly monotheistic, because monotheistic religions recognize only one God and make no mention at all of others. The very instruction not to worship other gods demonstrates recognition of those gods—if they do not exist, why instruct against it?

I don’t know how to begin answering such a strange argument. Idol worship is forbidden because many people did it back then. How you got from that to the conclusion that the Torah recognizes their existence is beyond me.

If the Torah only meant to forbid idol worship as such in the practical sense, then of course that doesn’t prove it recognizes other gods. It’s just that to me the verse “You shall have no other gods before Me” implies that there are other gods in the spiritual sense who exist and whom one may not worship. You can interpret it that way; it’s very reasonable.
If your interpretation is that this is a prohibition against idol worship and that it does not mean the gods people worship actually exist, then okay, that’s legitimate.
All in all, I brought the verse that led me to think this way—that perhaps it means actual gods whom one must not worship, and not simply a prohibition of idol worship as such.
And there’s no explosive argument here; it’s just a thought I had, that maybe this interpretation is legitimate and reasonable. If it seems strange to you, then so be it.

As a side note, one small comment—Asherah is not a Greek goddess but a Canaanite one (:

A linguistic note:
In the plural: the Ten Commandments. In the singular: one commandment.

Canaan son of Ham — after I sent the question, I checked afterward on Wikipedia and the like, and indeed I saw that it’s a Canaanite goddess.
Please — right, I thought about that later too. I also wrote “commandment” in my third comment (not including the question): “…the first commandment is an example of that…” etc.

But thanks for the corrections anyway 🙏

The meaning of “god” is absolute obedience to its words (the Rabbi wrote a whole column about this; I don’t remember which one, but it was in the last two months).
So when it says, “You shall have no other gods before Me,” the meaning is: do not obey any authority blindly except Me, the Lord.