"Can you consider the possibility that you don't understand what theism is?"
Can YOU consider the same possibility?

Hmm... if you want to learn about the US, whom do you think you should trust more, an American citizen or Saddam Hussein?

If I wanted to learn what theism is, I would never take an atheist's opinion seriously. The issue is not whether your perception of theism agrees with mine, the issue is whether my perception of theism agrees with other theists' perception of theism. In that sense, I can guarantee you that the only theists I have a problem with are fundamentalists.

I still think your perception of theism is based on what fundamentalists say.

I'm telling you, every theist I have ever met believes that God is physically out there.

Every theist I have ever met says "God is everywhere". Since they never pointed at a particular point in space and told me, "look, there's God, can't you see it", I take it they perceive God the same way I do. I also think God is everywhere, and nowhere to be seen.

Tell them that you believe that God is a useful mental exercise, that it's internal, and claim to be a theist and they will look at you like you have two heads.

I never said God is a useful mental exercise. I believe God is as real as my sense of self, and I don't think my sense of self is not real.

Is that to say that a belief in God's actual existence is idiotic?

What is idiotic is a belief in God's physical existence, as God is supposed to be the creator of everything physical and cannot be physical himself. A physical God could not be eternal, perfect, omniscient, and so on. Most theists agree with that.

True, but the label "red," though it may be interpreted by our brain, has its sources in reality (i.e. the wavelength of the light reflected by the object.)

Alright. If red comes from reality, where does reality come from?

But people still apply unfounded traits onto that universal source (such as sentience and emotion)

How do you know that the universe has no sentience and emotion? Aren't you a part of the universe? Where is it written that sentience and emotion come from a place that is not the universe? In a new-age book?

For you to dismiss our notions of God and still remain a theist amazes me. I've never seen anything like it. If it's just an acknowledged mental exercise, why should it comfort us and make us happy? It shouldn't, any more so than an adult should eagerly await for Christmas so Santa Claus will arrive.

I love this Santa Claus analogy, it's so silly it's funny.

Here's the story in a nutshell. You exist. Existing is good, and we are thankful for whatever it is that caused us to exist. Since "whatever it is that caused me to exist" is not myself, my emotional response to the fact that I exist must be projected onto something that is not myself. I call that something God, and I know God loves me almost by definition. The whole universe works in such a way that I exist. Can you appreciate the wonder of that? Can you also appreciate the fact that the world could have a million times more people and it would still be possible for you, Mario Dovalina, not to exist?

Intellectual Inquisitor? Do I really come across as that harsh?

I was joking. I just find it too silly and naive to demand that everyone justifies what they say or do, when most people are concerned about far more important things, such as paying their heating bills.

If you want to talk about why I think science is a reliable source of information, that could be fun, too.

Do you know how to treat other people? How to treat nature? Whom to trust? How to vote? How to raise children? What to do with your life? If you do, I'm sure you didn't learn those things from science. If you say you don't need religion for that kind of knowledge, I suggest you take a closer look.

Like it or not, the only alternative to religion is barbarism.