Agnosticism (noun)

1. The belief that the existence of a higher power or the truth of religious claims cannot be known or proven.
2. The belief that the existence of God or the truth of religious claims cannot be known or proven.

Origin:

Agnost- + -icism.

Examples:

1. He described himself as an agnostic, unsure if a higher power existed.
2. Agnosticism is the belief that the existence of God cannot be known or proven.
3. He was an agnostic, he did not believe in the existence of God.
4. The question of God's existence is central to agnosticism.
5. Agnosticism is often seen as a middle ground between atheism and theism.