Christianity Is Just As Bad
When you criticize Islamic supremacism, a very common response you'll get is something like this: "Christians do the same thing. Look at the Inquisition. Look at the Crusades. More people have been killed in the name of Christianity than all other religions combined."
You can find an answer to the Crusades part here: What About The Crusades?
An excerpt from Islam 101, authored by Gregory M. Davis:
The obvious response to this question is, "Well, what about them?" Violence committed in the name of other religions is logically unconnected to the question of whether Islam is violent. But, by mentioning the Crusades, the hope of the Islamic apologist is to draw attention away from Islamic violence and paint religions in general as morally equivalent.
In both the Western academia and media as well as in the Islamic world, the Crusades are viewed as wars of aggression fought by bloody-minded Christians against peaceful Muslims.
While the Crusades were certainly bloody, they are more accurately understood as a belated Western response to centuries of jihad than as an unprovoked, unilateral attack.
. . .
Muslim rule in the Holy Land began in the second half of the 7th century during the Arab wave of jihad with the conquests of Damascus and Jerusalem by the second "rightly-guided Caliph," Umar.
. . .
In the 11th century, the relatively benign Arab administration of the Holy Land was replaced with that of Seljuk Turks, due to civil war in the Islamic Empire.
. . .
The Turks resumed the jihad in the Holy Land, abusing, robbing, enslaving, and killing Christians there and throughout Asia Minor.
. . .
It was in this context of a renewed jihad in the Middle East that the Roman Pope, Urban II, issued a call in 1095 for Western Christians to come to the aid of their Eastern cousins
. . .
It's worth noting that the most ardent Crusaders, the Franks, were exactly those who had faced jihad and razzias (raids) for centuries along the Franco-Spanish border and knew better than most the horrors to which Muslims subjected Christians.
At the time of the First Crusade, the populations of Asia Minor, Syria, and Palestine, though ruled by Muslims, were still overwhelmingly Christian. The "Crusading" campaigns of the Western Christian armies were justified at the time as a war liberating the Eastern Christians, whose population, lands, and culture had been devastated by centuries of jihad and dhimmitude. Conquering territory for God in the mode of jihad was an alien idea to Christianity and it should not be surprising that it (Christian holy war) eventually died out in the West and never gained ascendancy in the East.
A simple way to answer the rest of the objection is: "Today, more people are killed in the name of Islam every year than were killed in the entire 350 years of the Spanish Inquisition." Direct your listener to see how many people are being killed daily in the name of Islam at TheReligionOfPeace.com. Memorize that URL so you can recommend it. Write it down for them. It is a site that documents every verifiable act of jihad in the world where at least one person is killed.
Another answer is: "In the 1400-year history of Islam, 270 million people have been killed in the name of Islam. No other religion even comes close. Communism doesn't even come close. Naziism doesn't either. The reason we don't know this is that Islamic supremacists have infiltrated the textbook publishing business in America and have massively edited the history of Islam. They also heavily influence Western media."
And lastly, Muhammad borrowed many ideas from both Judaism and Christianity, and that's why it bears a superficial similarity to familiar religions. But it is fundamentally different. You can find a thorough answer to this objection focused on their doctrinal differences here: Why I'm Worried About Islam But Not Christianity.
If you have ever responded to this objection with something you found particularly effective, please share it with us here. Thank you.