Unbelief (noun)

1. The state of not believing or having faith in something.
2. The absence of belief.

Origin:

From un- + belief.

Examples:

1. His unbelief in God was well-known.
2. She met with disbelief and unbelief when she shared her ideas.
3. The unbelief of the skeptics made it hard for them to accept the evidence.
4. The unbelief of the crowd was palpable.
5. His unbelief was evident in the way he spoke about the matter.