Great guestion! Michael Persinger has indeed come up with a theory that says that experiences of God can be ‘induced’ by the right king of electro-magnetic influence on the brain. See here for example. In fact, this theory has been around for quite a few years now. The conclusion that Persinger draws (and others, I might add) is that because we can stimulate the brain in such a way as to have a religious experience, or some other kind of experience like seeing UFO’s, it is no longer feasable to believe in God.
But why should we accept this conclusion? My television has an arial that is capable of detecting electromagnetic signals because there is a station that transmits them. It was designed for that purpose. In fact, the arial is an important part of what makes my television work. If I remove the arial and find that I no longer receive signals I do not conclude that the arial was unneccessary simply because I do not believe there are signals (after all, I can not see the signals). Similarly, if I send signals to the arial myself in some kind of experament and get a picture on the TV then I do not by this conclude that there is no broadcasting station.
It would seem to me that an equally valid conclusion to Persinger’s data is that God has created us with a spiritual ‘arial’ by which we might perceive a spiritual reality. The Bible teaches that human beings were created for the purpose of knowing God. If this is true then it is certainly not infeasable that we have brains that are capable of perceiving spiritual realities. Now, God certainly does not choose to regularly allow us to ‘see’ spiritual reality. But it should not surprise us that he has equipped us with brains that can when he wants us to.
Now, please don’t misunderstand. I am not saying that spiritual reality is electrochemical. But our brains are. If I stimulate a particular area of my brain then my arm will move, another area and I will see colour. These are false sensations, created by electrochemical impulse. Again, similarly, I might stimulate the part of my brain that is equipped to perceive spiritual reality and pick up a false sensation. This does not thereby falsify the entire spiritual reality any more than making me ‘see’ colour by stimulating the visual area of my brain falsifies the reality of colour!
Hope this helps.