The phrase "haddest doubts" refers to the feeling of uncertainty or indecision that one might experience about a particular situation, decision, or belief. The antonyms for this phrase would be words that describe the opposite feeling, such as confidence, certainty, assurance, or conviction. These words convey a sense of trust, assurance, and belief in oneself and one's abilities, which can help to dispel any doubts or hesitations that may arise. By using these antonyms in place of "haddest doubts," one can express a more positive and optimistic attitude towards a situation, and feel more capable and empowered to take action.