The question of Islamophobia is one being debated heavily today. Both politically and theologically, Islam appears in the general discourse of multiple countries and faith groups around the world. Seeking to know what Early Friends felt about the matter, I did some research. What I read and now share with you is likely to be controversial, but I would like to say before I proceed any further that I have no agenda to advance. What follows are the exact words of George Fox, the founder of Quakerism.
I suppose one who is setting up a new faith must differentiate it from those already extant. George Fox's perspective and tact differs considerably between passages. The 17th century wording sometimes takes a little while to understand, but it's not impossible to read.
From Vol. 4, The Works of George Fox, Doctrinal Books I
Friends,—...And this is the command of the Lord God to you, and you all, who rules kingdoms and kings with his mighty hand, which is his mighty power, as he does the waters...who sent his Son, who is the life of men, the Saviour of the world, the great and mighty prince of peace, the covenant of God with mankind...that he will be worshiped in spirit and in truth: the spirit that mortifies sin, the truth, the devil and sin is out of, for by your Muhammad have you been deceived, which saint is set up; therefore is the dreadful presence of the Almighty God, the everlasting Father of life appeared among you, and to you; unless you regard and embrace his voice, his power, his command, [the] mighty God of power, of dominion, and of dominions, who rules over all nations, heaven and earth; [unless you regard all of these, God] will seize upon you, and surprise you, and take you at unawares, and bring his judgments and dread upon you, which is now appeared in this the day of his Son; and the hour of his judgment is come, and coming upon all the world, of the mighty God of heaven and earth, of the mighty righteous God of heaven and earth, who in righteousness reigns, and in truth and equity.
An answer to the speech or declaration of the great Turk, and others by George Fox A Modern Answer to the Muslims' Belief That They Serve God By Killing Christians and Jews
I find in a paper, which is said to be thy declaration, directed to Leopold, the German emperor, dated the 25th of March, 1683, viz.
...You say you are a ‘possessor of the sepulcher of your God,’ to wit, the Christians. And that you are a great persecutor of the Christians.
Now, here is something in answer to the words of sultan Muhammad, the emperor of the Muslims, saying, he is a great persecutor of the Christians...but all things are naked and open unto the eyes of him, with whom we have to do, who are the true Christians, in scorn called Quakers, who do fear, serve, and worship the great God that made us, who is a consuming fire to the wicked. And where ever men do turn themselves, there the face of God will meet them; his divinity extends through the whole world. Therefore you are to fear his divine majesty, as you do confess in your Qur'an; for the great God, the creator of all, does know all in the heavens, and in the earth, both what is done in secret, and openly, and all is naked before him, who will reward every man and woman, according to their words and works, whether they be good or evil, for God is a consuming fire to the wicked; and who shall dwell with everlasting burning, but the just and holy?
And, Muhammad said in his Qur'an, Chapter 3, page 34, that Jesus said, ‘Who shall sustain the law of God in my absence? And the apostles answered him, we will sustain the law of God in thy absence;’ and that ‘Jesus shall be a witness in the day of judgment against such that obey not his law,’ &c.
Now see how you Muslims do obey the law or command of Jesus, for Jesus said, ‘Love your enemies, bless them that curse you, do good to them that hate you, pray for them that despite fully use you, and persecute you, that you may be the children of your Father which is in heaven.' Mat 5:44-45
Now if the Christians were the Turks' enemies, according to the command and law of Jesus, the Muslims are to love and bless them that curse them, and do good to them that hate them, and pray for them that despitefully use them and persecute them; so then the Muslims are not to be persecutors, if they do obey the command of the Lord Jesus Christ, and if they be the children of God the Father which is in heaven.
Apparently radical Islam has existed for quite a while. Here, a Turkish sultan is persecuting Christians. Noting passages in the Koran, as well as Islam's inclusion of Jesus' ministry, Fox states that Muslims aren't being faithful if they aren't following Jesus' teachings. In this case, this means loving one's enemy.
In a time where many Christian groups sprung up simultaneously and fought for converts, Fox calls his faith "the true Christianity". Many faith groups since then have argued this indirectly, some even now. Quakers no longer believe this.