What one thing would disprove Christianity to you?

[Undeceived]

Then they would no longer be nonmaterial. If some "miracle" force healed people every time you did a certain procedure, we would call that force natural. The scientific method measures repeatable phenomena. If an event is repeatable, it must be natural.

If you assume that something non-material, by definition, cannot affect the material, then you should no longer classify the myths of Christianity (your god, angels, human souls etc) as non-material.

The key here is the nonmaterial does not, by scientific standards, affect the material in a repeatable way. The moment we see it is repeatable (as are all things tested by the scientific method), we call it 'natural' whether it is or not-- we call them "natural laws": we observe them but do not understand why they are what they are. The cause may be nonmaterial at its origins, but science would never pronounce it so. For example, scientists are still looking for the smallest particle that determines attraction, weight, and every other law applied to matter. If naturalists ever got to that point, they would stop looking for a smaller particle and just assume that one as their premise going forward. Never mind why the particle is a law in itself, and how it came to be a law in itself, science is concerned only with natural phenomena. When it comes to the brink of the supernatural, when a nonmaterial cause is even hinted at, science stops and simply accepts what is before it. You know this is true. Is it fair?