Why might one know God is real, but not believe he is?

Similar to knowing you’re colorblind, but refusing to accept it subconsciously. Or for example, the existence of God feels like common knowledge to you and you still don’t feel like pursuing him? Where does conviction come from & how do you begin to feel it when something feels so real to you that you consider it a fact, but still feel nothing? How can one be even remotely possible of sinning willfully while knowing the punishment it merits and the pain it causes the Lord unless they do not truly believe (or else they would immediately feel overcome with sorrow and repentance for sinning.)