Christianity has an 800 year head start on Islam, what were Christians doing to people in the year 1200? They were roasting witches at the stake up until the 1700s and openly committing violence against homosexuals as late as this century
It took hundreds of years for Christianity to secularize to a point that's palatable for modern society, and if it hadn't, it wouldn't exist as we know it today
I see what you're doing there but its asinine. Just because Christianity began 800 (really 600) years before Islam does not mean that these societies exist in a vacuum and progress through the same changes at the same rate.
Islamic culture has steadily regressed over the last 1400 years, they peaked around the 9th Century, stayed fairly cosmopolitan and advanced until the battle of Lepanto and they lost control of the Mediterranean and the Ottoman Empire began a steady and steep decline.
Christianity rose in a period where the Roman Empire was in turmoil. The west went through successive disaster after disaster. Attila the Hun, The Viking era, the Islamic expansion squeezing Europe between southern France and the gates of Vienna. The middle ages were a bleak and ignorant period in Europe but it cannot be said to be entirely the fault of Christianity.
Christianity nor Islam creates the circumstances that they exist in entirely. While all that medieval barbarism was going in in western Europe the eastern Europe Byzantine Christians were as enlightened as they had ever been. They were under pressure from Islam and finished off by the Western Crusaders. It took Christian Europe 400 years to throw off the yolk of darkness.
Islam has been in that same Dark period since the Mongols destroyed Baghdad, they were ran out of Spain, and the last flicker of light went out in Anatolia and Islamic culture, unlike western culture, seems to thrive in the dark.