C.S. Lewis on the importance believing something because it's true:
"Christianity is not a patent medicine. Christianity claims to give an account of facts- to tell you what the real universe is like. Its account of the universe may be true, or it may not, and once the question is really before you, then your natural inquisitiveness must make you want to know the answer. If Christianity is untrue, then no honest man will want to believe it, however, helpful it might be: if it is true, every honest man will want to believe it, even if it gives him no help at all." 
Courage and Godspeed,
1. C.S. Lewis as quoted by Ken Boa in Passionate Living: A Devotional- Wisdom and Truth.