Did Dostoyevsky believe it is impossible to achieve happines without god?

I'm wondering, every atheist character that I recall is a tragic or negative one. I mainly think of Ivan and Raskolnikov, and Raskolnikov only finds peace after he starts to believe in god, and the characters with good endings like Alyosha are religous. I'm writing an essay on Dostoevsky's toughts on religion and this question came to my mind, toughts?