Religion is a belief that there is a higher power that rewards good and punishes evil.

Are you claiming all evil in the world is being punished and all good is being rewarded? What is good? What is evil? Are you aware that different religions across time and space had different notions of it? Are you claiming this omnipotent entity decided and some how bothered to communicate it to a human?

If I would have told you that this being and me spoke earlier, how would you respond?

Imagine being an omnipotent entity, and what you do for ages is meddling in human drama. Human centric much? What about different life forms? We are not the only intelligence in this planet. What about lifeforms on different in the universe? Are they also under the same scrutiny?

A place a person can look at the dark times in life to believe things will get better, and the world isn't as dark and awful as it can feel.

Yeah, that is completely delusional. But even worst, it's causing a lot of harm to others. Back to the earlier point - what if I told you that the omnipotent being told me religion is evil? I can find a lot of arguments to support the moral claim that it is evil and thus makes its practitioners do evil. Just so you could live in some little lie thinking you are better the all the rest.

Religion is also not for everyone, and some use religion to lie and manipulate others.

See? You support evil doers

But someone looking to religion for guidance in a time when they feel lost isn't some "mental illness".

Of course it is, what possibly could be solved by clinging to a full blown manipulative delusion?

Edit - some formatting