The antonyms for the phrase "hast no doubt" are many and diverse, ranging from uncertainty, hesitation, and skepticism to disbelief, mistrust, and suspicion. In essence, the opposite of being without doubt is to be filled with uncertainty and suspicion about something. This could manifest in many forms, such as doubting oneself, second-guessing one's decisions, questioning the intentions of others, or simply feeling unsure and hesitant in a given situation. Regardless of the context, the antonyms for "hast no doubt" all stem from a fundamental lack of confidence and trust, which can be debilitating and disempowering if left unchecked.