The phrase "most gainsaying" means to dispute or contradict something in the strongest way possible. The antonyms for this phrase would be words or phrases that convey the opposite meaning, such as accepting, agreeing, approving, believing, confirming, praising, recognizing, or acknowledging. These antonyms describe a state of mind that is open and receptive to new ideas and information, rather than one that is resistant or skeptical. By using these antonyms, one can demonstrate a more positive and inclusive approach to communication, which can help to build stronger relationships and foster greater understanding between people.