Well, that and the inescapable fact that no Jesus = no heaven. People think as long as they get along and lead a decent life, that's enough. If they believe in God at all, it's as a ol' buddy that they can ask for favors once in a while, and blame when things go wrong.
And being a Christ follower generally comes with a lot of worldly penalties - "as the world hates Me it will also hate you."
The Word is sweet and good (and necessary), but it has its bitter side, and people need to understand that both aspects of it are true. We can be so addled that we forget we have eternal life and joy in Him, and focus on present miseries.