The Qur'an was sent as affirmation to all the previous books. (Baqarah, 2/97; Ali 'Imran, 3/3; Ma'idah, 5 /48) Because all divine books came from the same source. The belief of tawhid and the true religion have continued since Prophet Adam and reached perfection with Islam. Prophet Muhammad (saw) is the last link of the chain of prophets. Therefore, it is natural that the Qur'an informs the same basic truths that were revealed to the previous prophets. 

From the Qur'an's affirmation of the previous books, it is understood primarily the faith in the oneness of Allah (swt) (tawhid) and the other aspects that are necessary for this belief. Secondly, the Qur'an affirms the moral principles contained in the previous books, such as justice, goodness, chastity, righteousness, halal earnings. Universal provisions, which are for the benefit of all humanity and do not change with the change of nations and time, are among the ones affirmed by the Qur'an. Apart from these, the Qur'an corrects the defects of holy books such as the Torah and the Gospels, which has been partially falsificated over time, and affirms their original state and presents them to humanity in new forms of expression. 

The Qur'an also affirms the news of the previous books about the coming of the Prophet Muhammad (saw). Because the previous books foretold the coming of a great prophet in the future. If the Prophet Muhammad (saw) had not come, this news they gave would have been unfounded. By acknowledging these news, the Qur'an affirms and proves the prophethood of not only the Prophet Muhammad (saw) but also all previous prophets. 

The Qur'an contains many similar topics with other books. Since He is Allah (swt) who has sent down all the divine books, it is natural to find similarities between them. For example, many of the subjects in the Gospels are also mentioned in the Qur'an. Qur'an mentions Zakariya (Zechariah), Yahya (John), Maryam (Mary) and Isa and the apostles; events such as the heralding of the birth of Isa to Maryam and the miracles of Isa. The similarity of expressions in the following two sections in the Qur'an and the Gospel is remarkable: 

“Muhammad is the Messenger of Allah; and those with him and their description in the Gospel is as a plant which produces its offshoots and strengthens them so they grow firm and stand upon their stalks, delighting the sowers- so that Allah (swt) may enrage by them the disbelievers. Allah (swt) has promised those who believe and do righteous deeds among them forgiveness and a great reward.” (Fath, 48/29)

“He told them another parable: “The kingdom of heaven is like a mustard seed which a man took and planted in his field. though it is the smallest of all seeds, yet when it grows, it is the largest of garden plants and becomes a tree. so that the birds come and perch in its branches.” (Matthew, 13/31-32). Tahir ibn Ashur states that there are similarities between the 29th verse of Surah Fath and some passages of Torah. (Ibn Ashur, XXVI, 207.)

Faith in books is one of the principles of faith. To be a mu'min, it is necessary to believe that Allah (swt) sent books to people. To believe in the books before the Qur'an means to believe in their pristine forms.

Some prophets have been given scriptures in history. However, these scriptures have not reached our time. The scriptures in question and the Qur'an come from the same source. Since the Qur'an contains permanent principles and provisions regarding the religion of Allah (swt), it also includes the information in the previous scriptures.

The Israelites were given a book called the Torah. Allah (swt) spoke directly to Prophet Musa on Mount Tur and revealed to him the relevant part of the Torah. However, this book has faced both interpretation and text falsification by believers. However, there is no falsification of the entire Torah. Indeed, in today's Torah, there are some provisions regarding the true religion; and there are sections that heralds the coming of Prophet Muhammad (saw). The provision of Torah removed with the revelation of Qur'an. The criterion that will determine how much and which parts of this book have been falsificated is the Qur'an, the only book that has not been tampered with. 

Allah (swt) revealed the Psalms to Prophet Dawud. It is known that the Psalms are a book of advice, consisting of words of prayer, glorification and praise taught to Prophet Dawud. However, the Psalms, which are included in the Bible as the book of Psalms today, are the falsified or later written version of the book sent to Prophet Dawud. Muslims believe in the Psalms that revealed to Prophet Dawud.

A book called the Gospel was revealed to Prophet Isa. Some similarities between the Qur'an and the Gospel show that both come from the same source. However, it is understood that the Gospel, like the Torah, was also subject to falsification. Christians replaced the belief of tawhid with the trinity, and the fact that Prophet Isa was a human prophet chosen from among people with the belief that he was an embodied god. The Qur'an states that these beliefs are superstitious. Muslims believe that a book called the Gospel was revealed to Prophet Isa by Allah (swt), they adopt the parts of today's Gospels that are compatible with the Qur'an and authentic hadiths, and reject the contradictory ones. 

The Qur'an is a word that belongs entirely to Allah (swt), both in wording and meaning. Jibrail (Gabriel) and Prophet Muhammad (saw) are means of conveying the revelation to us. When the Qur'an was revealed, it challenged people to make and bring a similar book, but even though centuries have passed since its revelation, nothing similar to it could be produced. Unlike other books, the Qur'an has survived to the present day without any human intervention. The truths it contains are universal and do not lose their value with the passage of time. Because it is the last divine book sent to people living in all ages.