i kind of disagree with Mr Lewis. I think the importance of christianity is to help us - to remind us - to lead loving lives with tangable benefit on this earth. So even if it's untrue, its still a very good plan for how to live ones life.
“… the greatest detractor from high performance is fear: fear that you are not prepared, fear that you are in over your head, fear that you are not worthy, and ultimately, fear of failure. If you can eliminate that fear—not through arrogance or just wishing difficulties away, but through hard work and preparation—you will put yourself in an incredibly powerful position to take on the challenges you face" - Pete Carroll.