The American Heritage® Dictionary

Noun: Belief in the existence of a god or gods, especially belief in a personal God as creator and ruler of the world.

 

Merriam-Webster

Noun: Belief in the existence of a god or gods; specifically: belief in the existence of one God viewed as the creative source of the human race and the world who transcends yet is immanent in the world.

 

Theism 101: What is Theism? Who are Theists? Believing in God and Gods

Austin Cline

What is Theism?:

To put it simply, theism is a belief in the existence of at least one god – nothing more, nothing less. Theism does not depend upon how many gods one believes in. Theism does not depend upon how the term ‘god’ is defined. Theism does not depend upon how one arrives at their belief. Theism does not depend upon how one defends their belief. That theism only means “belief in a god” and nothing more can be difficult to understand because we don’t normally encounter theism in isolation. Read More…

What is a Theist?:

If theism is the belief in the existence of at least one god, then a theist is anyone who believes in the existence of at least one god. They may believe in a single god or in multiple gods. They may believe in a god which is transcendent to our universe or in gods which dwell all around us. They may believe in gods which 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 like.