Is no Religion a Religion.

[Sejanus]

Theism = religion. Atheism = without religion.
How hard is that to understand?

Sorry, that's not what those words mean. Neither theism nor atheism are relgions. Anthropologically speaking, a religion could be atheistic. Some arguably are, or at least border on it. A ton of Unitarians are also atheists, for instance.

Theism=believes in at least one God or god.
Atheism=does not believe in at least one God or god.

Doesn't that definition apply more to deists? I took theism to mean belief in and worship of a personal god, (which is religion), and atheism do be the negation of theism.