Suffering Causes Religion

I'm not sure the thesis suffering caused religion, because human life is marked by suffering. But we have to be careful about correlation versus causation. So I would say that religion is a natural instinct that human beings have. There's even been cognitive research showing this instinct within children. Even in Judaism, we don't see a progressive rebel as you noted. We see a progressive revelation of this,. though I take issue that the Old Testament also includes elements of describing God's tender care to help people through suffering.