How to believe without evidence

I am a christian, but of course like all i struggle with belief. My most common and intense struggle is when i am at a bad place, i sinned, i think to myself but there is no evidence of god. Like no facts that he exists, like in science. But especially when i feel bad, i feel very apart from god, i pray but sometimes it does not change anything. How can i uphold my faith even in my darkest moments when the thoughts of that there is no evidence that he exists arise.