It's difficult to summarize close to two millenia of Islam, and all its impact on every Islamic and European nation, and do so with complete accuracy.

The overview of the decline of Islam is worthwhile.

But I dislike that Islam and Christianity are spoken of as two interchangeable religions.
quote:
(from the above article):

...it's irresponsible to insist that some inherent quality of the Islamic religion perpetuates ignorant fanaticism. Islam is much like Christianity, in that you can find something in it to justify almost any fool notion.

I find this sweeping statement about Christianity unfounded and insulting. It clearly has a contempt for Christianity, a level of bias and contempt that makes me wonder if the rest of what the writer says could possibly be accurate.

Islam is far more conquest-oriented and brutal at its root. The early spread of Islam was through conquest for hundreds of years, and putting any in conquered areas who would not convert to Islam "to the sword".

Christianity is far more peaceful at its root, and in its first 300 years, never had an army fight and conquer in its name. It was Constantine who first aligned with Christians and granted them the right to freely practice Christianity in the Roman Empire, and began the more secular influence of Christianity over armies and politics, that became the Roman Catholic church.
But BEFORE Constantine, Christianity had already spread to every corner of the Roman Empire. Christianity had already spread throughout the empire peacefully, it was only recognition and the freedom to practice Christianity openly that Constantine offered.

The Inquisition, under the Roman Catholic Church, was an abberation and temporary corruption of the church, where the average Christian didn't have access to Bible teachings themselves, and had to rely on the interpretation of a corrupt clergy, which led to the Reformation, begun my Martin Luther in 1517, and other reformers.
And the Inquisition and Crusades were also a direct result of Islamic invasion deep into European/Christian territory. It was more of a taking back what had been taken from them, with some obvious excesses that were done in the name of Christianity, but were clearly more political than religious.

Once printing presses made the Bible widely available to individuals, Christianity changed dramatically, and regained the peaceful nature that had been lost. Those fleeing the stranglehold of Rome on Europe, came to Pennsylvania and the other English colonies, to practice Christianity in a way more consistent with the Bible. And establish government that guaranteed the free practice of true Christianity, in a new form of government strongly based in Christian principles.

Universities, science, humanitarian aid, hospitals, and democracy are all innovations that came from the Christian community.

I recognize that Islam has made some contributions in these areas as well, but I don't like seeing Christianity block-labelled in the same category as Islam.