Many people “believe” in a spiritual world or in God. But believing is not the same as perceiving, and we do not only perceive with our six senses.
When you live in a cave and never go outside, you may “believe” in the sun but you never feel its warmth on your skin. The belief does not warm you. Believing is not perceiving.
There is a way of perceiving the so-called “spiritual” realm without believing in it. In fact, believing in it prevents it from being perceived.