深信不疑

Deep; depth; far; very; profound; intense; late; thick; dense; flourishing.

to believe; to trust; to be convinced; letter; mail; message; news; truthful; confidence; at will

Function word; no; not; un-; negative prefix; used to form questions or emphasize a statement; sometimes used for rhythm.

To doubt; to suspect; to hesitate; to be uncertain; to be perplexed; to fear; to seem like.