The physics professor had just finished his lecture about the pendulum, wherein he had shown the mathematical proof that an untouched pendulum will always swing in ever-decreasing arcs.
He then asked for a volunteer to demonstrate this fact by standing against a wall with a pendulum bob against his chin, then releasing the bob and allowing the pendulum to swing naturally through its arc. The professor reminded the class that the bob would return almost to, but not quite touching, the chin.
No one volunteered. Although the science students “believed” this law of physics was true, they were unwilling to prove it in their lives.
How like many of us in our relationship with God! We know the facts, but are unwilling to risk a step of faith based on them.