the twenty sixth call: the obligation of believing in allah and his messenger
almighty allah says (what can be translated as): "o you who have believed, believe in allah and his messenger and the book that he sent down upon his messenger and the scripture which he sent down before. and whoever disbelieves in allah, his angels, his books, his messengers, and the last day has certainly gone far astray." (al-nisaa': 136)
almighty allah commands his believing servants to believe in him alone with no partners, his kind messenger muhammad (peace be upon him), the book he sent upon his messenger (the qur'an), the books that were sent by allah earlier on his kind messengers and prophets. allah warns them against the consequences of disbelief. he says to them that whoever disbelieves in allah, his angels, his books, his messengers and the last day has certainly drifted away from the path of guidance and gone far astray from the truth.
it is the belief in allah and his messenger that connects the hearts of believers to their lord who created them and sent the prophet muhammad (peace be upon him) to guide them. it is also a belief in the message of prophet muhammad (pbuh) and accepting all what he conveyed to them from their lord who sent him as a messenger to guide them.
it is the belief in the book that was revealed to the messenger (pbuh) to connect them with the method chosen by allah almighty for their life; he clarified this method in the book (the qur'an). they have to take and follow everything in that book since the source is one and the method is one. there is no part of this book that has priority over other parts in terms of reception, acceptance, obedience and application.
it is also the belief in the books that was revealed prior to the qur'an since the source of all the books is one, namely almighty allah. the foundation of these books is also one which is submitting one's face to allah and distinguishing him, exalted and sublime be he, with all the characteristics of worship. it is the admittance that the method of allah is the only method that has to be obeyed and applied in life. this unity is the natural and logic requisite as all of these books – before they were distorted – are revealed by allah. the method of allah is one, his will concerning humans is one and his path is one. other paths are misleading and divided while this path is directly leading to him.
the belief in all the books – all the books are one book in fact – is the character that distinguishes the muslim nation. the understating of this nation of the one lord, the one method and the one path is the understanding with which the fact of lordship, the unity of humanity, the unity of the undivided truth become straight and fall right into place. anything other than this truth is error. "and what can be beyond truth except error" (yunus: 32). after the command of belief comes the warning against disbelieving in the elements of faith. almighty allah clarifies these elements that we have to believe in before the mention of the punishment: "and whoever disbelieves in allah, his angels, his books, his messengers, and the last day has certainly gone far astray."
almighty allah mentions in the first command, at the beginning of the verse, the belief in allah, his books and messengers but he does not mention the angels. the books of allah include the mentioning of the angels and the last day and logically one of the requisites of the belief in these books is the belief in the angels and the last day. yet, almighty allah mentions the belief in the angels later in the verse because it is a warning and threat, so he details every element in specific.
"has certainly gone astray" implies the meaning of the extreme delusion and error with which there is no hope for guidance or expectation of reaching the destiny.
whoever disbelieves in allah, even though the natural disposition believes in him willingly and naturally, the angels, the books, the messengers and the last day, (disbelieving in them comes as a result of disbelieving in allah), then his nature has reached a degree of corruption with which no guidance can be expected and no destiny can be foreseen.