Funny, I upvoted this because of the artistic and cultural contributions of religion. For most of history, until the Industrial Revolution or a little before, human economies were Malthusian. You could not increase incomes without decreasing average lifespans. The implication is that the money spent on cathedrals and gargoyles and all the rest came directly at the expense of people's lives. (A recent Steven Landsburg debate with Dinesh D'Souza explored this line of thinking more; I wouldn't recommend watching much more than the opening statements, though.)

I think the positive externalities of having more of those people's descendants alive today would be of higher value than the current benefits of past art--especially since most of that past art has been destroyed.