We do accept that the scriptures are inspired based on faith. We can’t epistemologically reason our way to determine whether something written thousands of years ago was divinely inspired. I agree that we need common ground, so-called “preambles of faith” that are based on evidence we can access with reason and observation. The metaphysical existence of God, the historical evidence of the church and the bible, and the empirical investigation of miracles today may provide some common ground.
It depends on what you accept as discovery. There are rational arguments for the subsistence and indissolubility of the soul in the philosophy of mind, but this is not going to provide direct empirical observation of something that is immaterial, although we are intimately familiar with the material effects at every moment.
And sure you could set up experiments about exorcists or miraculous healings if you’d like. Please do! That sounds really interesting and I’d like to read what you suggest.
The difference with these possible non-physical entities is we are not investigating natural processes, but personal agency. How would you set up an experiment? It would be something like para-psychology, perhaps. As for prayer, it is not a magic spell, either. It’s like setting up an experiment and telling people to ask someone for something, and then saying, well, they got half “Yes” and about half “No” so asking people for things is not effective.