1) Astonishment 2) Disbelief 3) Skepticism 1) Disbelief 2) Distrust 3) Doubt 4) Doubtfulness 5) Dubiety 6) Dubiousness 7) French word used in English 8) Incertitude 9) Incredulousness 10) Mental rejection 11) Mistrust 12) Pyrrhonism 13) Scepticism 14) Skepticism 15) Uncertainty 16) Unwillingness to believe 17) Want of faith 
• (n.) The state or quality of being i/credulous; a withholding or refusal of belief; skepticism; unbelief; disbelief.
In`cre·du'li·ty noun [ Latin incredulitas : confer French incrédulité .] The state or quality of being incredulous; a withholding or refusal of belief; skepticism; unbelief; disbelief. « Of every species of incredulity , religious unbelief is the most irrational.» 
[n] - doubt about the truth of something
incredulity 1. A disbelieving frame of mind; unreadiness or unwillingness to believe (statements, etc.); disbelief. 2. A state or feeling of disbelief. There are two ways to slide easily through life; to believe everything or to doubt everything; both ways save us from thinking. —Alfred Korzybski
disbelief noun doubt about the truth of something
the quality or state of being incredulous; inability or unwillingness to believe.