Is religion the opiate of the elite?

Andrew Gelman claims religion is the “opiate of the elite,” from this graph:

He says:

Religious attendance predicts Republican voting much more among the rich than the poor.

This is a really interesting phenomenon — condition on wealth and see different effects of religion.

But from looking at that graph, I saw the flipped interpretation — condition on religion, then see different effects of wealth (each line has a different slope).  Only the religious become more Republican with greater wealth; secular voters don’t change their preferences when they get rich.