Is the world of ordinary experience, of living from one moment to the next, going up and going down, illusory? If we saw things the way they really were, would we say that the world of our experience is the real world, or is some other reality real.
One school of Hinduism, Advaita Vedanta, says the is one reality, and it is the spritual reality of Brahman. It is one. The idea that I am a distinct person from you is an illusion. If I go to prison tomorrow, it's not real. If I win the lottery tomorrow, it's not real. Brahman, the true God whom we cannot even define with our words, that's what's real.