What’s “crazy,” specifically? The concept that a human being is an integrated whole, body-soul, so that actions done by the person have physical and spiritual meaning? Or that rejecting something integral to the person, such as his or her capacity to produce a new life, is contradictory in a relationship (marriage) that is supposed to create the One-ness of two people?
Or do you just think Christianity in general is crazy?
And, I suggested a different purpose, a more functional purpose that might make more sense.