Theists feel the need to believe in God because they're afraid of attributing their religion to themselves. They lack conviction, so they don't want to be responsible for the ideology they believe in.
If you believe in God, you never have to stand on your own. You can always look up to someone. In the actual words of a theist I talked to about this, "you can be a child forever".
I found this thought very interesting. I imagine any reasonable theist who reads this is insulted, so feel free to leave a comment telling me how I'm full of shit.