As I imagine it is around the world, British elections seem to consist mostly of mud slinging. In particular, two parties stand out: Labour, and the Conservatives (a.k.a. the Tories). It is seemingly inevitable that whenever one of them wants your vote, they will immediately begin to tell you the bad things about the other party.
I remember specifically a canvasser who came to my door. After hearing I wasn't planning on voting Labour, she immediately jumped to "but if you don't vote Labour, you'll get the Tories". So I replied with "that's like saying if I don't vote to lose my left arm, I lose my right." She panicked. What I had just done is effectively asked her to provide me with a reason I should vote Labour, not for a reason I shouldn't vote for the Tories. And she clearly hadn't been trained for that.
The realm of British politics is not the only place this kind of argument happens. In religious debate, you see it quite a lot. Let's look at three examples.
The first example is Islam and the Crusades. Islam is a notoriously violent religion. In fact, thereligionofpeace.com holds an annual event called the Ramadan Bombathon dedicated to recording the number of Islamic terror attacks committed during Ramadan compared to every other religion worldwide, specifically recording Islamophobic attacks during the same period. Islam consistently dominates. When I originally wrote this article, it was Ramadan 2019, and the score stood at 81 Islamic attacks, totalling 369 kills, with 0 attacks by other religions, and only one Islamophobic attack, killing one Muslim. There is, of course, a reason for this. Islam's sources tell us that Muhammad was a terrorist and a war criminal who commanded his followers to do likewise. Thus, we shouldn't be surprised when they do likewise.
But the Islamic retort often involves accusations of violence, which they direct against alternative views. In particular, Islamic apologists and their allies love to point to the Crusades. There are several problems with this. First, the Crusades were a defensive response to Islamic aggression. Islam started taking over the world, the Catholic Church decided this wasn't exactly ideal, so they started fighting back. Second, the Crusades were a Catholic campaign, and so if this argument worked, it would only work against Catholics. It has no effect on Christianity, or even atheism. Third, the Crusades happened centuries ago, whereas Islamic terror still happens. Finally, even if the Crusades weren't defensive, were a Christian campaign, and still happened in the modern day, one religion being violent does not excuse another religion being violent. "Christianity is evil" is not the same as "Islam is good".
The second example is the Catholic Church's argument from denominations. This is an argument they frequently present. But again, does exaggerating the number of Protestant denominations, and pointing to corruptions within a few of those, justify the Catholic Church? Not by a long shot.
And finally, you have the Origins debate. Evolutionists, generally speaking, are terrible at defending their religion, but none of them are as incapable of mocking Creationism. But if Creationism was false, would that prove Evolution true? Not at all. In fact, if I was not a Creationist, I would probably be a lot ruder in bashing Evolution, because the only reason I am currently so restrained from this is because I believe Jesus wants me to be.
Appealing to the worst parts of opposing worldviews may well open the door for your own to be accepted, but just opening the door is not enough to convince someone to walk through it. Attacking another worldview is not the same as proving your own worldview. "You're bad, therefore I'm good", or "like your view is any better", aren't valid arguments.
Christianity does not need to bash other religions to prove itself true. Instead, it hangs its entire case on one historical event: The resurrection. If Christ is not risen, Christianity is a fake, and with it, Judaism also dies, because the time limit for the Messiah is long gone. But if Christ is risen, nothing else can be valid.
The resurrection is not only the proof of Christianity, but the point of Christianity. When Jesus died, He was dying in your stead. He took the punishment you deserve for rebelling against God, and because He took your punishment, you can receive His reward. In Christianity, salvation takes only the confession of Christ as Lord, and the heartfelt belief that He rose by God's power. Vote Jesus, not because Satan is bad, but because Christ is Lord.