I spoke with a sceptic and described the experience of chanting the Maha Mantra, and she said roughly this:
You can't prove that any of that is metaphysically true. The shift in consciousness you describe could be a psychological effect of believing in the mantra and in God. In that case you are just seeking a pleasant experience, and the motivation to that is hedonism.
To which I replied:
Yes, you have a point, but your view is based on nihilism; the assumption that nothing is sacred, that sanctity is a human invention, that life is nothing beyond matter. My view is based on the hope that sanctity is real and exists by itself. The hope that there is a reality beyond banality. The search for sanctity needs no motivation, it is its own motivation. It is life seeking its own reality.