Debate teaches you to argue both sides. After that, it’s hard to hate people who disagree.

Once you have had to build the other side’s case properly, it stops being possible to believe they are all stupid or lying. You have stood in the position yourself and felt where it holds together. That does not mean you switch, it means the disagreement gets smaller and more specific. Contempt needs ignorance to survive.

Pick something you feel strongly about and write the strongest version of the opposite view in three sentences. If you cannot do it without sneering, you do not understand it yet.