Are poor, dumb people more likely to be religious? Yes, there is a tendency there. If one were to suddenly become well educated would they also become atheist? Possibly, one can hope. It has certainly happened before.

However, calling atheism "white supremacy" would only be valid if you're also saying only black people are poor and dumb, and that sounds a lot more like a you problem than an atheism problem. A class struggle is not required for atheism: everyone is welcome to join in. The fact that people who don't understand the world or universe can be duped by religious mumbo jumbo is just a fact, not a requirement or defining feature.