We have an effect on the lives of others whether or not we have beliefs based on faith. But, it seems to be worth noting that those effects which come from faith may be beneficial to others, even to those who have no faith.

I admit to being a little lost, however. Your analogy between the shipbuilder's faith in his boat and a Christian's faith in god is a bit off the mark. The shipbuilder's faith has a physical manifestation; a Christian's faith does not usually manifest itself physically. An exception might be the faith in God's healing power.