“深信不疑”，汉语成语，形容对事对人非常相信，没有半点怀疑。可以翻译为“believe firmly，be convinced of，believe without a shadow of doubt”等。

例句：

他对大蒜的医学功效深信不疑。

He had an invincible faith in the medicinal virtues of garlic.

他对上帝的存在深信不疑。

He is positive to believe in the being of god.