Therapists sometimes reference secondary gains when dealing with patients. A secondary gain is an unconscious or hidden motivation for a person to be ill. For example, a boy might become sick but he might get to stay home from school, watch his favorite movie and get loving attention from his mom. (all examples of secondary gains)
A person of doubt might have secondary gains as well. Maybe the secondary gain is being so sure of the absence of God that you write a book that makes a lot of money. Maybe the secondary gain is that you get to make fun of Christians. Maybe it get's you attention.
Or... maybe the secondary gain is that now that you don't believe in Him, God wont interfere with your life. Now you can live however you want, think whatever you want, do everything you want to do without conviction.
Anything is permissible if there is no God. - Dostoevsky
Of course, to be fair, faith has secondary gains as well. What might they be?