Is believing in the predestination (qadar) and Allah’s decree (qada) a pillar of Islamic creed? The short answer is…
Destiny and Allah’s decree are not mentioned in the verses that talk about the principles of faith (Baqarah, 2/177, 285; Nisa, 4/136). However, this principle is emphasized in the verses that point out to the fact that everything depends on the decree and predestination of Allah as well as the ones that indicate the divine knowledge encompasses all beings and incidents that happened in the past and will happen in the future. In some of these verses, Allah the Exalted states, “…And everything with Him is by due measure.” (Ra‘d, 13/8); “… and has created each thing and determined it with [precise] determination.” (Furqan, 25/2); “Say, “Never will we be struck except by what Allah has decreed for us…” (Tawbah, 9/51)
In addition to these verses, the verses which inform us about the facts that Allah is the creator of everything, that He leaves some servants in perversion and guides some others to the right path in accordance with the choice of the servant, and that He predestines the time of death of people (see Zumar, 39/62; Saffat, 37/96; A`raf, 7/178; Waqi‘ah, 56/60, etc.) reveal that everything in the universe is dependent on a certain destiny in terms of scope and that this is determined by Allah. In the hadith known as “the hadith of Jibril,” the Prophet (saw) mentioned destiny among the things that should be believed. According to this hadith, when Jibreel asked the Prophet “What is iman?”, he replied as, “That you affirm your faith in Allah, in His angels, in His Books, in His Apostles, in the Day of Judgment, and you affirm your faith in the Divine Decree about good and evil.” (see. Muslim, Iman, 1; Abu Dawud, Sunnah, 15; Ibn Majah, Muqaddimah, 9).
The scholars of ahl al-sunnah considered faith in qadar and qada among the pillars of iman within the framework of the verses and hadiths mentioned above.
Source: Presidency Of Religious Affairs The Turkey, High Board of Religious Affairs FATWAS