I don't know if this is "an insight" or just hooey, but i have a thought about "why God might allow us a believers continue to do stupid things that 'hurt His reputation'". ( I know this is a complicated issue and I'm not condoning the stupid things Christians do, but none of it catches God off guard. It's not like He didn't know how sinful and lame we are).
Could it be that He allows it so as to distinguish true believers, who love Him for who He is, from those who would use any reason to doubt Him?
Those who truly know God (and the truths of sin and grace) realize that God is bigger and greater than the weak vessels He has chosen to serve as His ambassadors.
Those who look at the "hypocrites in the church", etc and see an excuse not to trust God show that their focus is more on man than on God who has displayed his grace and love through Jesus. If the sinfulness of man trumps the grace shown through the cross then you've got your heart set on the wrong thing.
