The Six Pillars of Iman (Faith):
5) Belief in the Last Day (i.e. the Day of Judgment)
6) Belief in Divine Will and Decree (Al-Qada' wal-Qadar)
Two of the Pillars of Faith is to believe in Allah's books and Allah's Messengers. You will notice that this is plural. The reason being that as a Muslim, we have to believe in all the scriptures that were sent down before the Quran, and all the Messengers that were sent before the Prophet Muhammad.
We believe that there were four scriptures sent down in total:
1) the Tawraat (or Torah) which was sent with Prophet Musa (Moses)
2) the Zaboor (or Psalms) which was sent with Prophet Dawud (David)
3) the Injeel (or Gospel) which was sent with Prophet 'Isa (Jesus)
4) the Quran which was sent with Prophet Muhammad
The Prophets and Messengers that Allah sent were many, but Allah only mentions 25 in the Quran (listen below in chronological order):Adam, Idrees (Enoch), Nuh (Noah), Hud, Salih, Ibrahem (Abraham), Loot (Lot), Ismae'l (Ishmael), Ishaaq (Isaac), Ya'qoob (Jacob), Yuseuf (Joseph), Shu'ayb, Ayyoub (Job), Dhul-Kifl, Musa (Moses), Haroon (Aaron), Dawud (David), Sulayman (Solomon), Ilyaas (Elias), Al-Yasa' (Elisha), Yunus (Jonah), Zakarriya (Zachariah), Yahyaa (John), 'Isa (Jesus), and Muhammad.