‘The complete atheist stands on the next-to-last highest rung leading to the fullest and most complete faith (he may take that step, or he may not), but the indifferent man has no faith at all, except an ugly fear.’
Quote. It's very true. Kirillov was faithful as a monk in his man-god. Stavrogin is insane due to indifference; degenerate out of ennui.

