How should we understand the verse "O you who believe! Believe"?

Dear Brother / Sister,

The believers are ordered "to believe as it is necessary". The remaining part of the verse explains how it is necessary to believe.

"O ye who believe! Believe in Allah and his Messenger, and the scripture which He hath sent to His Messenger and the scripture which He sent to those before (him). And who denieth Allah, His angels, His Books, His Messengers, and the Day of Judgment, hath gone far, far astray." (an-Nisa, 4/136)

The interpretation of the verse:

O you who believe! Believe in Allah and His Messenger, that is Muhammad (pbuh) and this book, which Allah sends down from time to time and in parts to this Prophet, that is, the Quran, and the books He had sent down before. Believe in all of them as you believed in some of them. The word nazzala (sent down) is pronounced as nuzala and unzala (was sent down) (in the passive form) in the qiraah of Ibn Kathir, Abu Amr and, Ibn Amir. Believe in them seriously. For, anyone who does not believe in Allah, His angels, books, prophets and the Day of Judgment, and denies any of them goes far astray, goes away from the truth, loses his way in a way that he cannot find it again and loses his purpose. With this (an-Nisa, 4/116), it is clearly shown that he joins the decree of unbelief, that is, all kinds of unbelief is shirk (polytheism).

According to a narration, a group of Jewish rabbis went to the Messenger of Allah and said, "O Messenger of Allah! We believe in you, your book, Moses (Musa), the Torah and Ezra (Uzayr); we do not accept any other books and prophets." The Prophet (pbuh) said, "No! Believe in Allah, all of His prophets, Muhammad, the Quran, his book, and all of the books before it." They said, "No." Thereupon, this verse was sent down and all of them believed. It is remarkable that belief in four things is mentioned in the part of belief: "Belief in Allah, His Messenger, the book sent down to His Messenger and the book sent before it". This can be summarized in three levels as follows: "Belief in Allah, the Prophet and the books". However, in the part of belief, five things are mentioned with the addition of angels and the Day of Judgment: "Denying Allah, denying His angels, denying His books, denying his prophets and denying the Day of Judgment; besides, the other messengers were added to the Messenger of Allah and the word was used in plural. This shows that belief in Allah, the Prophet and the books included belief in all prophets, angels and the Day of Judgment; since it is possible for a person to believe in Allah, the Prophet and the books, and to deny one of the prophets, angels or the Day of Judgment and to try to interpret the verses that were sent down regarding the issue, it is especially explained that those who deny them deny Allah too. 

(Elmalılı H. Yazır, the interpretation of the relevant verse)

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