Great questions, Matt. Enjoyed reading your post.
Do they really believe? Christians, like anyone, are, I think, afraid. Afraid of being alone. Of failing, or being considered a failure. Of not being respected by thier peers. Of losing a job. Fill in the blank.
They want to be loved. To have time with friends. To have happy children. To be secure with their spouse. To have time for self.
Then someone says they need help. They just lost a job, or had a child arrested, or a spouse pack their bags.
To love that person risks nothing but reputation, and costs nothing but time. The thing we fear most and the thing we want most.
Jesus said that if one seeks his own life he will lose it, but if he/she loses it he will find it. "Trust me", he says, "and love others. And you will lose nothing and gain everything."
No one, not Billy Graham, not Mother Theresa and not me can follow this all the time, or maybe even most of the time. But if you do not see this in a person, yes, I think you have a right to ask the question: Do they really believe?