noun
distrust; mistrust; disbelief; loss of confidence
The main modern use: not trusting a person, organization, explanation, system, or claim. Common in compounds and phrases such as 不信感, 不信を抱く, and 不信を招く.
政府への不信が広がっている。
Distrust of the government is spreading.
彼の説明はかえって不信を
His explanation only invited mistrust.
noun
insincerity; bad faith; breach of trust
A less common sense referring to failure to act sincerely or to keep faith with someone; in modern usage, 不誠実 or 背信 is often clearer depending on context.
「不信の行為」は、「信義に反する行為」という意味で使われることがある。
The phrase 不信の行為 is sometimes used to mean an act done in bad faith.
noun
impiety; faithlessness; lack of religious faith
Religious or literary use for lack of faith or piety. In ordinary modern Japanese, 不信心 is often the more direct word for being irreligious or impious.
古い宗教的な文章では、「不信の徒」という表現が見られる。
In old religious writing, the expression 不信の徒 can be found.