Christian Theology in Plain Language, p. 97
Let us suppose that God's resources are so much beyond what we can imagine that he can produce a situation in which we can honestly say, "I see now that even the butchery of six million Jews doesn't matter. This is why he didn't do what I would have done if I had had the power to strike dead every Nazi in order to prevent it." This line of thought does not solve the problem of evil. But it points in the direction of a solution.
The idea goes back to Jesus. "A woman giving birth to a child has pain because her time has come; but when her baby is born she forgets the anguish because of her joy that a child is born into the world" (