Sometimes people want to convince you to do things that you don’t want to do, and which aren’t any of their business.
Sometimes people want to argue with you about politics, and aren’t…
If they’re being pushy and you care about them it may help to say “I have said no. Let’s change the topic,” and repeat until compliance. Putting the ‘no’ in past tense makes it more final, which is harder to argue. If they still want to argue, walk away. You can’t help if they think it’s rude when they’re not leaving you a polite option to defend your boundaries.
Yes, that works sometimes.