A denial of the existence of the universe as distinct from God.

Acosmism, in contrast to pantheism, denies the reality of the universe, seeing it as ultimately illusory, and only the infinite unmanifest Absolute as real.

This philosophy begins with the recognition that there is only one Reality, which is infinite, non-dual, blissful, etc. Yet the phenomenal reality of which we are normally aware is none of these things; it is in fact just the opposite: i.e. dualistic, finite, full of suffering and pain, and so on.

Since the Absolute is the only reality, that means that everything that is not Absolute cannot be real. So, according to this viewpoint, the phenomenal dualistic world is ultimately an illusion, regardless of the apparent reality it possesses at the mundane or empirical level.