Wallatheena yu'minoona bima onzila ilayka wama onzila min qablika wabil-akhirati hum yooqinoon (surah Baqarah: 4)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(2:4) who believe in the Book We have sent down to you (i.e. the Qur'an) and in the Books sent down before you, *7 and firmly believe in the Hereafter. *8

Wallazeena yu`minoona bimaa unzila ilaika wa maaa unzila min qablika wa bil Aakhirati hum yooqinoon

*7). The fifth requirement is that one should believe in the Books revealed by God to His Prophets in the various ages and regions of the world, in the Book revealed to Muhammad (peace be on him) as well as in those revealed to the other Prophets who preceded him. The door of the Qur'an is closed to all those who do not consider it necessary for man to receive guidance from God. It is also closed to those who, even if they believe in the need for such guidance, do not consider it necessary to seek it through the channel of revelation and prophethood, but would rather weave their own set of ideas and concepts and regard them as equivalent to Divine Guidance.
This door is also closed to those who believe in Divine books as such, but confine this belief to those books accepted by their forefathers, and spurn Divine Guidance revealed to anyone born beyond their own racial and national boundaries. The Qur'an excludes all such people and is prepared to open the source of its grace only to those who believe that mankind does require Divine Guidance, who acknowledge that this guidance does not come to people individually but reaches them through Prophets and Divine Books and who are not given to racial or national chauvinism but are devotees of Truth alone, and are therefore prepared to submit to Divine Guidance wherever it be found.
*8). Belief in the After-life is the sixth and last requirement. The term al-Akhirah embraces a whole set of ideas:
(i) that man is not an irresponsible being, but is answerable to God for all his conduct in this world;
(ii) that the present order of the world is not timeless, but will come to an end at an appointed hour knon only to God;
(iii) that when this world comes to an end God will bring into being another world in which He will resurrect, at one and the same moment, all the human beings ever born on earth. He will gather them together, examine their conduct and grant each one just reward for his actions;
(iv) that those who are accounted good in God's judgement will be sent to Heaven, and those judged by Him as evil-doers will be consigned to Hell;
(v) that the real measure of success and failure is not one's prosperity in the present life, but one's success or failure according to God's judgement in the Next.
Those who do not accept this set of beliefs can derive no benefit from the Qur'an. For if a man is merely in a state of doubt and hesitation with regard to these matters - let alone disbelieving them - he cannot advance even one step forward along the path charted out by the Qur'an.