Theism is a belief in the existence of at least one god - nothing more, nothing less. It does not depend upon how many gods one believes in. It does not depend upon how ‘god’ is defined. It does not depend upon how a believer arrives at their belief. It does not depend upon how the believer defends their belief. That theism simply means “belief in a god, ” and no more can be hard to understand because we rarely encounter theism in isolation.

What Is a Theist?

If theism is the belief in a god, then a theist is anyone who believes in the existence of at least one god. They may believe in a single god or multiple gods. They may believe in a god which is transcendent to our universe or in gods who dwell all around us. They may believe in gods who aid us actively or in a god which is disinterested in humanity. If you know that a person is a theist, you can’t make any automatic assumptions about what their god is or is not like, so you have to ask. Of course, they may not know either, given how many believers haven't reflected deeply on the details, but it's still up to them to explain.

Varieties of Theism

Theism has come in several varieties over the millennia: monotheism, polytheism, pantheism, and several more that many haven't even heard of. Understanding the differences between the different types of theism is necessary not just to understand the religious systems in which they appear, but also to understand the variety and diversity which exists for theism itself.

Theism vs. Religion

Many seem to believe that religion and theism effectively the same thing, such that every religion is theistic and every theist is religious, but that's a mistake that's based on a number of common misconceptions about both religion and theism. In fact, it isn't uncommon even among atheists to assume that religion and theism are effectively equivalent. The truth is that theism can exist independently of religion and religion can exist without theism.

Theism vs. Atheism: Burden of Proof

The idea of a “burden of proof” is important in debates because whoever has a burden of proof carries an obligation to “prove” their claims in some fashion. Some degree of a burden of proof (or just support, in most cases) always lies with the whoever is a claim, not with whoever happens to be hearing the claim and thus who may not initially believe the claim is true. In practice, this means that an initial burden of proof lies with the theist, not with the atheist.

Is Theism Irrational?

Theism doesn’t mean very much, at least not inherently, since it doesn't mean anything more than believing in the existence of at least one god of some sort. Why or how one has such a belief is no more relevant to the definition of theism than why or how one lacks belief in gods is relevant to the definition of atheism. One of the reasons why this is important is because it has significant implications for the question of whether theism is rational or irrational.

What Is God?

When a theist claims that a god of some sort exists, one of the first questions atheists should ask is "what do you mean by 'god'?" After all, without some understanding what the theist means, the atheist cannot even begin to evaluate the claim. By the same token, unless the theist is clear about what they mean, they cannot properly explain and defend their beliefs.