You debate somebody to give an equal opportunity to both sides to have a reasoned and civil exchange of ideas, so that those listening can make an informed choice.
There aren’t two sides, here. There is no civil exchange to be had. (To paraphrase NK Jemisin), you don’t debate who gets to be people.
There is nothing productive to be gained by “debate” with people that spout the slogans and cloak themselves in the symbolism of an ideology that has murdered millions of people. People who align themselves with an agenda of extermination don’t deserve your respect or your coddling, and they cannot be permitted to stand and speak unchallenged, anywhere, anytime. You do not engage in civilized debate, or reasoned discourse, with Nazis. You do not engage in a civil exchange of ideas with Nazis. You do not agree to disagree with Nazis.
You gather superior numbers and you link arms and you stand against them and you shout “never again” in their faces until your throat is raw. You shame them and denounce them and expose them as cowards and racists and as agents of evil. As long as you need to and as long as you have to.
And, well, they either back down, and crawl back under their rocks, or they don’t. We didn’t keep them under their rocks 80 years ago. We tried ignoring them and hoping they would go away 80 years ago. Tens of millions died, and we had to shoot them all. So we know that works, at least for a while. We should probably try to stamp out the fucking cockroaches before it gets to that point this time, but we know for a fact that ignoring them and hoping they go away does not work.
You don’t debate who gets to be people.