Make predictions with dialectical materialism and with mechanistic materialism, and then see which predictions were better

I'm in no position to quantitatively judge this by myself so, until presented with evidence that dialectical materialism objectively gives better predictive capabilities, I don't have any reason to study it.

The problem with Christianity is that the predictions it attempts to make are usually wrong

Well, yes, that was my point. I don't necessarily believe dialectical materialism is intrinsically better than mechanistic materialism.