Belief in divine books is the third article of faith in Islam. Thus, a Muslim is required to believe in all the books of Allah. “And who believe in what has been revealed to you, [O Muhammad], and what was revealed before you, and of the Hereafter they are certain [in faith]” (Quran, 2:4)
All the holy books were revealed as the uncreated word of Allah. Islam is ahead of the other Abrahamic faiths (Judaism and Christianity), with regard to its affirmation of Allah’s revelations. The Quran affirms the fact that Allah revealed divine books to His messengers: “We have already sent Our messengers with clear evidence and sent down with them the Scripture and the balance that the people may maintain [their affairs] injustice” (Quran, 57:25).
As for how many Islamic holy books there are, our Deen (Religion) confirms the existence of four clearly-named revelations. In the eras during which the scriptures were revealed, they sought to explain the purpose of life and people’s obligations. These included duties to Allah as well as humans. The books of Allah serve as proof against people, as they have no excuse for being disobedient or heedless. The names of these holy books, as per Islamic teachings, are Tawrat, Zabur, Injil, and Quran.