How to drive away a guy?

Today I ran into this guy I friendzoned a few months ago and now he's texting me again. He's not harassing me or anything. He's interesting and nice but I just don't like him back and I don't want to deal with his feelings. I think he likes me because he kinda sees me as an innocent ray of sunshine in this dark world and he's in a place right now where needs somebody to believe in him. I am a kind person though and I do believe in him and I don't wanna just start being mean and rude to him. I wish there was something else I could do to make him lose interest on his own so it doesn't have to come to a confrontation where I'd have to reject him and we'd both end up feeling bad.