It's a metaphysical assumption, meaning beyond the realm of experimental science. Science has inherent limitations, and cannot be used to explain everything. This is a good starting point: https://www.youtube.com/watch?v=If3cNUixEBM
Interesting how you just said science "cannot be used to explain everything" and yet now you're claiming "proof" and "evidence" (i.e. science) for your particular religion. Make up your mind.