Many a times I have witnessed a conversation similar to this one:
Theist to the Atheist: How come you do not believe in God?
Atheist: Simply, because I see no evidence for God’s existence.
Theist: If you only accept physical evidence, you will never find it, since God is not a physical being.
Atheist: So one cannot detect a supernatural being using physical means?
Theist: That is correct.
Atheist: And one cannot use physical methods to influence a supernatural being?
Theist: Also correct. Don’t forget, we are talking about supernatural beings, and they are not subject to the laws of physics.
At this point the conversation usually veers off onto a tangent of “how can one gain knowledge” about the supernatural, if direct discovery is impossible, and one cannot influence supernatural beings. This time let’s look at a different approach.
The church maintains a sizable number of exorcists. These exorcists perform some kind of “discovery method”, and attempt to find out if someone is possessed by “demons”. Then they also perform some physical rituals, and claim that the demons were expelled. The precise method of discovery and the method of the rituals is of secondary interest, the main point is that they are both observable, repeatable, physical endeavors.
As such the usual assertion that supernatural entities cannot be discovered or influenced by fully physical means is contradicted by the church’s own application of physical activities vis-à-vis some supernatural beings - aka demons.