Paul W. answered 04/04/19
Dedicated to Achieving Student Success in History, Government, Culture
Mohammed was most certainly known in 17th century Europe. Like Alexander and Caesar, no one could deny that Mohammed had irrevocably changed the course of history, for better or worse - and there was no doubt in the minds of Europeans on that score! While it's undoubtedly true that among some European scholars, who actually studied the contents of the Koran, there were selective words of admiration for some aspects of the Muslim Faith, overall, attitudes among 17th century Europeans towards Mohammed would have been strongly negative.
Except for those of the Jewish Faith, Europe in the 17th century was uniformly Christian, even if this consisted of mutually hostile denominations (Catholics, Lutherans, Calvanists, Anabaptists, etc...) They may not have agreed with each other's theologies, but one thing that they did agree on was that Mohammed was a product of Satan. Christians knew with absolute certainty that Jesus was the Son of God - not, as taught in the Muslim Faith, one among a series of God's prophets, the last of which was Mohammed. In the minds of 17th century European Christians, anything that contradicted the Bible was automatically the work of the Devil, lies intended to ensnare the souls of Christians. All Christian denominations taught that following the correct teachings of Jesus, contained in the Good Book and interpreted (differently) by Church leaders, was the only means by which an individual had any hope of earning a place in heaven and, thus, avoiding eternal punishment in hell. Thus, every Christian European knew, without question, that all Muslims were condemned to spend the afterlife in torment (just as all Muslims knew, without question, that all Christians were to suffer punishment in the afterlife for failing to heed the word of Mohammed).
It's important to note that, for 17th century Europeans, Islam was as much an actual threat as an ideological threat. The enormously powerful Ottoman Empire, which controlled much of the Middle East (excepting Persia), most of North Africa, and all of the Balkans, was actively seeking to overrun Central Europe. The Hapsburg city of Vienna had already undergone on e siege by the Turks in the 16th century and, before the end of the 17th century, would undergo yet another. European armies battled Ottoman forces in southeastern Europe, while Christian armadas fought with Ottoman squadrons in the Mediterranean. In other words, the issue of whether or not Islam would succeed in subjugating most, if not all, of Europe had not yet been definitively decided during the 17th century.