The antonyms for the word "altering conviction" could be steadfastness, resolution, certainty, and firmness. Steadfastness refers to being firmly committed to a belief or course of action without wavering. Resolution is the quality of making a firm decision to do or not to do something. Certainty means being completely sure about something and having no doubts or hesitations. Firmness is the ability to be strongly determined and unwavering in one's beliefs or decisions. These antonyms suggest a sense of stability and constancy that contrasts with the idea of changing or altering a conviction, which implies a lack of certainty or decisiveness.