Who is "they"? One nutjob misguided young Londoner who says he hates Jews and Christians "for the sake of Allah" and will chop people's heads off in a war is not 1.9 billion Muslims (aka ~25% of the global population) and not almost 90 million Iranians, if that's what you're presumably referring to. (Plus, Iran is very ethnically diverse and they're not all Muslim anyway. Iran also has a well-established Jewish community (2,700 years old) of up to 10,000 or even more, along with Arabs, Christians, Baháʼís and a number of other groups.)
That's not what said young man's whole religion teaches and plenty of actual Islamic scholars would disagree with him (possibly very strongly). Anyway, that Indian evangelical Arul Velusamy preacher guy who runs that channel is arguably a bit of a troll, no offence. His channel is full of heavily edited clickbait. Not that you can edit out stuff like said nutjob said, of course, so I agree there's no getting away from that, but still. A lot of it is in the genre of "X owns Y" and in reality the other person was just trying to explain their POV to him without him interrupting or shouting over them after he posed very complex questions, and he edits out half the conversation to make them look stupid. Similar to Charlie Kirk (a famous Trump-supporting Christian, who actually does talk a lot of sense, in my opinion, and to his credit generally tries to stay very civilized (he's a good speaker) but is also often guilty of this kind of thing in order to go viral). Helps their side hustle too.
He has other videos claiming stuff like the UK police are Shariah-sympathizers when all they did was politely ask him to stop interviewing a guy who didn't want to be filmed. (It's not generally illegal to film people in the UK, but if people don't want to talk or be filmed for your videos, you can't force them. Plus it's Speaker's Corner where the whole point is you're allowed to debate and have free speech about anything as long as you remain civil. But accusing them of being Shariah-sympathizers is pushing it a bit.)
Yes, it's disturbing that people like that young guy have those crazy disturbing views. You can also find unhinged US "Christians" and crazy Jewish settlers and all manner of crazy people who sympathize with ethnic cleansing and other immoral stuff. Doesn't mean they represent millions (or billions) of other people.
It's important not to generalize swathes of people based on a minority of people with extreme views.