All scripture is inspired by God and is useful for teaching, for refutation, for correction, and for training in righteousness, so that one who belongs to God may be competent, equipped for every good work. (2 Tim 3:16-17)

Know this first of all, that there is no prophecy of scripture that is a matter of personal interpretation, for no prophecy ever came through human will; but rather human beings moved by the holy Spirit spoke under the influence of God. (2 Pe1:20-21)

Letters have reached us too from that city, apart from which we are wandering: those letters are the Scriptures, which exhort us to live well. (Saint Augustine of Hippo. Expositions on the Psalms, Psalm 91, no. 13)

Accordingly, He who sent the prophets before His own descent also dispatched the apostles after His ascension. Moreover, in virtue of the man assumed by Him, He stands to all His disciples in the relation of the head to the members of His body. Therefore, when those disciples have written matters which He declared and to them, it ought not by any means to be said that He has written nothing Himself; since the truth is, that His members have accomplished only what they became acquainted with by the repeated statements of the Head. For all that He was minded to give for our perusal on the subject of His own doings and sayings, He commanded to be written by those disciples, whom He thus used as if they were His own hands. (Saint Augustine of Hippo. Harmony of the Gospels, 1, 35, 54)

I heard him, indeed, every Lord’s day, ‘rightly dividing the word of truth’ (Tim 2:15) among the people; and I was all the more convinced that all those knots of crafty calumnies, which those deceivers of ours had knit against the divine books, could be unravelled. (Saint Augustine of Hippo. The Confessions, Book VI, ch. III)

[It has been decided] that nothing except the Canonical Scriptures should be read in the church under the name of the Divine Scriptures. (Denzinger-Hünermann 186. Council of Carthage III (397), Canon of the Sacred Scripture, 397)

Still, the Christian faith is not a “religion of the book”. Christianity is the religion of the “Word” of God, “not a written and mute word, but incarnate and living”. (St. Bernard, S. missus est hom. 4, 11: PL 183, 86) If the Scriptures are not to remain a dead letter, Christ, the eternal Word of the living God, must, through the Holy Spirit, “open (our) minds to understand the Scriptures.” (Cf. Lk 24:45) (Catechism of the Catholic Church, no. 108)

If anyone, however, should not accept the said books as sacred and canonical, entire with all their parts, as they were wont to be read in the Catholic Church, and as they are contained in the old Latin Vulgate edition, and if both knowingly and deliberately he should condemn the aforesaid traditions let him be anathema. Let all, therefore, understand in what order and in what manner the said Synod, after having laid the foundation of the confession of Faith, will proceed, and what testimonies and authorities it will mainly use in confirming dogmas, and in restoring morals in the Church. (Denzinger-Hünermann 1504-1505. Council of Trent, Session IV, Decree about Canonical Scriptures, April 8, 1546)

Furthermore, this supernatural revelation, according to the faith of the universal Church, as declared by the holy synod of Trent, is contained “in the written books and in the unwritten traditions which have been received by the apostles from the mouth of Christ Himself; or, through the inspiration of the Holy Spirit have been handed down by the apostles themselves, and have thus come to us” [Council of Trent, see n. 783]. And, indeed, these books of the Old and New Testament, whole with all their parts, just as they were enumerated in the decree of the same Council, are contained in the older Vulgate Latin edition, and are to be accepted as sacred and canonical. But the Church holds these books as sacred and canonical, not because, having been put together by human industry alone, they were then approved by its authority; nor because they contain revelation without error; but because, having been written by the inspiration of the Holy Spirit, they have God as their author and, as such, they have been handed down to the Church itself (can. 4). (Denzinger-Hünermann 3006. Vatican Council I, Session III, Dogmatic constitution Dei Filius, Ch. 2, April 24, 1870)

Those divinely revealed realities which are contained and presented in Sacred Scripture have been committed to writing under the inspiration of the Holy Spirit. For holy mother Church, relying on the belief of the Apostles (see Jn 20:31; 2 Tm 3:16; 2 Pt 1:19-20, 3:15-16), holds that the books of both the Old and New Testaments in their entirety, with all their parts, are sacred and canonical because written under the inspiration of the Holy Spirit, they have God as their author and have been handed on as such to the Church herself. In composing the sacred books, God chose men and while employed by Him they made use of their powers and abilities, so that with Him acting in them and through them, they, as true authors, consigned to writing everything and only those things which He wanted. (Vatican Council II. Dogmatic constitution Dei verbum, no. 11, November 18, 1965)

Sacred theology rests on the written word of God, together with sacred tradition, as its primary and perpetual foundation. By scrutinizing in the light of faith all truth stored up in the mystery of Christ, theology is most powerfully strengthened and constantly rejuvenated by that word. For the Sacred Scriptures contain the word of God and since they are inspired, really are the word of God; and so the study of the sacred page is, as it were, the soul of sacred theology. (Vatican Council II. Dogmatic constitution Dei verbum, no. 24, November 18, 1965)

Therefore, since everything asserted by the inspired authors or sacred writers must be held to be asserted by the Holy Spirit, it follows that the books of Scripture must be acknowledged as teaching solidly, faithfully and without error that truth which God wanted put into sacred writings for the sake of salvation. Therefore ‘all Scripture is divinely inspired and has its use for teaching the truth and refuting error, for reformation of manners and discipline in right living, so that the man who belongs to God may be efficient and equipped for good work of every kind’ (2 Tim. 3:16-17) (Vatican Council II. Dogmatic constitution Dei verbum, no. 11, November 18, 1965)

These points now being briefly established, viz., regarding the deity of Christ, and the fulfilment of all that was prophesied respecting Him, I think that this position also has been made good, viz., that the Scriptures themselves, which contained these predictions, were divinely inspired — those, namely, which had either foretold His advent, or the power of His doctrine, or the bringing over of all nations (to His obedience). To which this remark must be added, that the divinity and inspiration both of the predictions of the prophets and of the law of Moses have been clearly revealed and confirmed, especially since the advent of Christ into the world. For before the fulfilment of those events which were predicted by them, they could not, although true and inspired by God, be shown to be so, because they were as yet unfulfilled. But the coming of Christ was a declaration that their statements were true and divinely inspired, although it was certainly doubtful before that whether there would be an accomplishment of those things which had been foretold. (Origen. De Principiis, Book IV, no. 6)

If anyone, moreover, consider the words of the prophets with all the zeal and reverence which they deserve, it is certain that, in the perusal and careful examination thus given them, he will feel his mind and senses touched by a divine breath, and will acknowledge that the words which he reads were no human utterances, but the language of God; and from his own emotions he will feel that these books were the composition of no human skill, nor of any mortal eloquence, but, so to speak, of a style that is divine. The splendor of Christ’s advent, therefore, illuminating the law of Moses by the light of truth, has taken away that veil which had been placed over the letter (of the law), and has unsealed, for everyone who believes upon Him, all the blessings which were concealed by the covering of the word. (Origen. De Principiis, Book IV, no. 6)

If we ask how we are to explain this power and action of God, the principal cause, on the sacred writers we shall find that St. Jerome in no wise differs from the common teaching of the Catholic Church. For he holds that God, through His grace, illumines the writer’s mind regarding the particular truth which, “in the person of God,” he is to set before men; he holds, moreover, that God moves the writer’s will – nay, even impels it – to write; finally, that God abides with him unceasingly, in unique fashion, until his task is accomplished. Whence the Saint infers the supreme excellence and dignity of Scripture, and declares that knowledge of it is to be likened to the “reassure” and the “pearl beyond price,” since in them are to be found the riches of Christ and “silver wherewith to adorn God’s house.” (Benedict XV. Encyclical Spiritus Paraclitus, no. 9, September 15, 1920)

There are many other extraordinary and quite ridiculous things in this book which he boasts was sent down to him from God. But when we ask: ‘And who is there to testify that God gave him the book? And which of the prophets foretold that such a prophet would rise up? They are at a loss. And we remark that Moses received the Law on Mount Sinai, with God appearing in the sight of all the people in cloud, and fire, and darkness, and storm. And we say that all the Prophets from Moses on down foretold the coming of Christ and how Christ God (and incarnate Son of God) was to come and to be crucified and die and rise again, and how He was to be the judge of the living and dead. Then, when we say: How is it that this prophet of yours did not come in the same way, with others bearing witness to him? And how is it that God did not in your presence present this man with the book to which you refer, even as He gave the Law to Moses, with the people looking on and the mountain smoking, so that you, too, might have certainty? They answer that God does as He pleases. This we say, ‘We know, but we are asking how the book came down to your prophet. Then they reply that the book came down to him while he was asleep. Then we jokingly say to them that, as long as he received the book in his sleep and did not actually sense the operation, then the popular adage applies to him (which runs: You’re spinning me dreams.) (Saint John Damascene. On Heresies, no. 105, PG 94, 766)

And so down to the time of Heraclius they were very great idolaters. From that time to the present a false prophet named Mohammed has appeared in their midst. This man, after having chanced upon the Old and New Testaments and likewise, it seems, having conversed with an Arian monk, devised his own heresy. […] He says that there is one God, creator of all things, who has neither been begotten nor has begotten. [112:3] He says that the Christ is the Word of God [3:45; 4:171] and His Spirit, but a creature [3:59] and a servant, [4:172; 19:30; 43:59] and that He was begotten, without seed [3:47; 19:19-22; 21:91], of Mary [2:87, 2:53; 3:45; 4:157; 61:6, etc] the sister of Moses and Aaron. [19:28] For, he says, the Word and God and the Spirit entered into Mary [4:171; 21:91; 66:12] and she brought forth Jesus, who was a prophet [3:39, 19:30; etc.] and servant of God.
And he says that the Jews wanted to crucify [4:157] Him in violation of the law, and that they seized His shadow and crucified this. But the Christ Himself was not crucified, he says, nor did He die, [4:157] for God out of His love for Him took Him to Himself into heaven. [4:158] And he says this, that when the Christ had ascended into heaven God asked Him: O Jesus, didst thou say: “I am the Son of God and God”?’ And Jesus, he says, answered: ‘Be merciful to me, Lord. Thou knowest that I did not say this and that I did not scorn to be thy servant. But sinful men have written that I made this statement, and they have lied about me and have fallen into error.’ [5:116; 19:88-91; 39:4; 112:3, etc.] And God answered and said to Him: I know that thou didst not say this word.’ (Saint John Damascene. On Heresies, no. 101, PG 94 766)

Turks and other infidels […] They treat the way of true light and salvation with complete contempt and totally unyielding blindness; they attack the life-giving cross on which our Saviour willed to accept death so that by dying he might destroy death, and by the ineffable mystery of his most holy life he might restore life; and they make themselves hateful enemies of God and most bitter persecutors of the Christian religion. Strengthened by defences not only spiritual but also temporal, we may be able, under God’s guidance and favour, to oppose the bitter and frequent sallies by which, in wild rage, they move savagely amidst Christian blood. (Lateran Council V, Session XII, Against those attacking the houses of cardinals, March 16, 1517)

Obviously we cannot agree with these various forms of religion, [Judaism, Moslem and Afro-Asiatic] nor can we adopt an indifferent or uncritical attitude toward them on the assumption that they are all to be regarded as on an equal footing, and that there is no need for those who profess them to enquire whether or not God has Himself revealed definitively and infallibly how He wishes to be known, loved, and served. Indeed, honesty compels us to declare openly our conviction that the Christian religion is the one and only true religion, and it is our hope that it will be acknowledged as such by all who look for God and worship Him. (Paul VI. Encyclical Ecclesiam suam, no. 107, August 6, 1964)

Nor do divine pronouncements on the part of preceding prophets offer him (Mohammed) any witness. On the contrary, he perverts almost all the testimonies of the Old and New Testaments by making them into fabrications of his own, as can be. seen by anyone who examines his law. It was, therefore, a shrewd decision on his part to forbid his followers to read the Old and New Testaments, lest these books convict him of falsity. It is thus clear that those who place any faith in his words believe foolishly. (Saint Thomas Aquinas. Summa contra Gentiles, Book I, ch. 6, no. 4)

The point is clear in the case of Muhammad. He seduced the people by promises of carnal pleasure to which the concupiscence of the flesh goads us. His teaching also contained precepts that were in conformity with his promises, and he gave free rein to carnal pleasure. In all this, as is not unexpected, he was obeyed by carnal men. (Saint Thomas Aquinas. Summa contra Gentiles, Book I, ch. 6, no. 4)

The Mahometan paradise, however, is only fit for beasts; for filthy sensual pleasure is all the believer has to expect there. (Saint Alphonsus de Liguori. The History of Heresies and their Refutation, pg. 93)