lack of faith; unbelief; impiety; infidelity
Refers to the absence or rejection of religious faith, or a state of not believing. Often used in religious or moral contexts.
His lack of faith saddened his family.
I was taught that unbelief is a sin.
Compound of 不 (fu, 'not') + 信仰 (shinkō, 'faith, belief'). The prefix 不 negates the following noun, forming a straightforward antonym.