If this world is only in the mind, why can't I fly, cast a Fireball spell, or instantly make Myself taller, thinner, younger, or even turn into a dragon?
Faith. That's the thing, and its the reason why no Christians, ever, have ever been able to move a mountain. Because their faith is far, far too small, smaller even than a mustard seed.
Its why heaven is empty. No Christian has enough faith to change reality, ergo not enough faith for salvation.