The opposite of "alters conviction" would be reinforcing conviction. Reinforcing conviction means strengthening one's beliefs and opinions, rather than changing or weakening them. This could happen through experiences, conversations, or research that provide new evidence or reinforce existing beliefs. Another antonym for altering conviction might be solidifying conviction, which suggests making one's beliefs even more firmly held and unwavering. These ideas stand in direct opposition to the notion of altering conviction, which implies a shift in perspective or opinion. While altering conviction is sometimes necessary, reinforcing or solidifying conviction can also be a powerful tool for maintaining conviction in one's beliefs and values.