If you accept the "two-world assumption," you are vulnerable to skepticism.

Two-World Assumption

The belief in a distinct separation between the tangible, empirical world and an intangible, often spiritual or theoretical world.

Skepticism

The philosophical belief that knowledge is not possible, that doubt will not be overcome by any valid arguments. A philosopher who holds this belief is called a skeptic. Skepticism is not merely personal doubt but also requires systematic doubt, with reasons for that doubt.