Belief in books of Almighty Allah
All the Ambiya of Almighty Allah were sent with Books of Guidance to teach and educate the people.
Many Holy Books were sent by Almighty Allah to the world.
A Muslim believes in all the Books sent by Almighty Allah.
The four famous Books are:-
A. TORAH (Old Testament) : sent to Nabi Moosa (alayhis salaam)
B. ZABOOR (Book of Psalms) : sent to Nabi Dawood (alayhis salaam)
C. INJEEL (New Testament) : sent to Nabi 'Isa (alayhis salaam)
D. HOLY QURAN : sent to our Nabi Muhammad
The Angel, Sayyiduna Jibra'el (alayhis salaam), used to convey Almighty Allah's Message to the Ambiya.
The Torah, the Zaboor and the Injeel are still found in the world today, but they have been changed by the Jews and the Christians.
Nothing has changed in the Holy Quran. It is still the same as it came to our Nabi Muhammad because Almighty Allah Himself has promised to protect the Holy Quran.