This is what the great martyrologist John Foxe says about Islam, why we should be knowledgeable about it, and the only successful way to combat it.
“If it were not that I fear to overlay this our volume with heaps of foreign histories, who have professed chiefly to treat of Acts and Monuments here done at home, I would adjoin after these popes known above rehearsed, some discourse also of the Turks’ story; of their rising and cruel persecution of the saints of God, to the great annoyance and peril of Christendom. Yet, notwithstanding, certain causes there be, which necessarily require the knowledge of their order and doings, and of their wicked proceedings, their cruel tyranny and bloody victories, the ruin and subversion of so many christian churches, with the horrible murders and captivity of infinite Christians, to be made plain and manifest, as well to this our country of England, as also to other nations.
“First, For the better explaining of the prophecies of the New Testament, as in St. Paul's Epistle to the Thessalonians, and also in the Revelation of St. John; which scriptures otherwise, without the opening of these histories, cannot so perfectly be understood: of which scriptures, we mind hereafter (Christ granting) orderly, as the course of matter shall lead us, to make rehearsal.
“Another cause is, that we may learn thereby, either with the public church to lament, with our brethren, such a great defection and decay of christian faith, through these wicked Turks; or else may fear thereby our own danger.
“The third cause, that we may ponder more deeply with ourselves the scourge of God for our sins, and corrupt doctrine; which, in the sequel hereof, more evidently may appear to our eyes, for our better admonition.
“Fourthly: The consideration of this horrible persecution of the Turks rising chiefly by our discord and dissension among ourselves, may reduce us again from our domestical wars, in killing and burning one another, to join together in christian patience and concord.
“Fifthly: But chiefly, these great victories of the Turks, and un- prosperous speed of our men fighting against them, may admonish and teach us, following the example of the old Israelites, how to seek for greater strength to encounter with these enemies of Christ, than hitherto we have done. First, we must consider that the whole power of Satan, the prince of this world, goeth with the Turks; which to resist, no strength of man's army is sufficient, but only the name, spirit, and power of our Lord Jesus the Son of God, going with us without in our battles; as among the old Israelites the ark of God's covenant and promise went with them also fighting against the enemies of God. For so are we taught in the Scripture, that we christian men have no strength but in Christ only. Whether we war against the devil, or against the Turk, it is true that the Scripture saith, ‘Sine me nihil potestis facere,’ that is, ‘Without me you can do nothing.’ Otherwise there is no puissance to stand against the devil, or to conquer the world, ‘nisi fides nostra,’ that is, ‘our faith only,’ to which all the promises of God touching salvation be annexed; beyond which promises we must not go, for the word must be our rule. He that presumeth beyond the promises in the word expressed, goeth not, but wandereth he cannot tell whither: neither must we appoint God how to save the world, but must take that way which he hath appointed. Let us not set our God to school, nor comprehend his Holy Spirit within our skulls. He that made us without our council, did also redeem us as pleased him. If he be merciful, let us be thankful. And if his mercies surmount our capacity, let us therefore not resist but search his Word, and thereunto apply our will; which if we will do, all our contentions will be soon at a point. Let us therefore search the will of our God in his Word, and if he will his salvation to stand free to all nations, why do we make merchandise thereof? If he have graciously offered his waters to us, without money or money-worth, let us not hedge in the plenteous springs of his grace given us. And finally, if God have determined his own Son only to stand alone, let not us presume to admix with his majesty any of our trumpery. He that bringeth St. George or St. Denis, as patrons, to the field, to fight against the Turk, leaveth Christ, no doubt, at home.
“Now how we have fought these many years against the Turk, though stories keep silence, yet the success declareth. We fight against a persecutor, being no less persecutors ourselves. We wrestle against a bloody tyrant, and our hands be as full of blood as his. He killeth Christ's people with the sword, and we burn them with fire. He, observing the works of the law, seeketh his justice by the same: the like also do we. But neither doth he, nor do we, seek our justification as we should, that is, by faith only in the Son of God. And what marvel then, our doctrine being as corrupt almost as his, and our conversation worse, if Christ fight not with us, fighting against the Turk? The Turk hath prevailed so mightily, not because Christ is weak, but because Christians be wicked, and their doctrine impure. Our temples with images, our hearts with idolatry are polluted. Our priests stink before God for adultery, being restrained from lawful matrimony. The name of God is in our mouths, but his fear is not in our hearts. We war against the Turk with our works, masses, traditions, and ceremonies: but we fight not against him with Christ, and with the power of his glory; which if we did, the field were won.
“Wherefore, briefly to conclude, saying my judgment in this behalf, what I suppose. This hope I have, and do believe, that when the church of Christ, with the sacraments thereof, shall be so reformed, victory, that Christ alone shall be received to be our justifier, all other religions, merits, traditions, images, patrons, and advocates set apart, the sword of the Christians, with the strength of Christ, shall soon vanquish the Turks' pride and fury. But of this more largely in the process of this story.
“The sixth and last cause, why I think the knowledge of the Turks' cause, history requisite to be considered, is this: because that many there be, who, for that they be further from the Turks, and think therefore themselves to be out of danger, take little care and study what happeneth to their other brethren. Wherefore, to the intent to excite their zeal and prayer to Almighty God, in this so lamentable ruin of Christ's church, I thought it requisite, by order of history, to give church this our nation also something to understand, what hath been done in of Christ. Other nations by these cruel Turks, and what detriment hath been, and is like more to happen by them to the church of Christ, except we make our earnest invocation to Almighty God, in the name of his Son, to stop the course of the devil by these Turks, and to stay this defection of Christians falling daily unto them, and to reduce them again to his faith, who are fallen from him: which the Lord Jesus of his grace grant with speed! Amen.
John Foxe, Acts and Monuments, Book VI
John Foxe, Acts and Monuments, Book VI