Among the fundamental beliefs of the Deen of Islam is that Allah Ta‘ala is Aalim-ul-Ghaib. Aalim-ul-Ghaib means that Allah Ta‘ala has the complete and perfect knowledge of everything and there is nothing that is hidden from the knowledge of Allah. Allah Ta‘ala has the complete knowledge of the past, present and future. The aqeedah of the Ahlus Sunnah wal-Jamaa’ah is that the one who does not believe in Allah Ta‘ala having complete and perfect knowledge is out of the fold of Islam, as he has disbelieved in the verses of the Qur’aan and the authentic Ahaadith of Rasulullah (sallallahu ‘alaihi wasallam).
As far as the Shia are concerned, they have invented a belief known as badaa and claim that until and unless one does not subscribe to this belief, he can never be a perfect believer. (Usool-ul-Kaafi 1/146)
Badaa literally means for something which was initially invisible and unclear to become visible and clear to one later on. Hence, according to the shia belief of badaa, it is possible for Allah Ta‘ala to learn of something which He was previously unaware of, thus causing Allah Ta‘ala to change His decision. In this way, the shia attribute ignorance to Allah Ta‘ala.
The shia use this belief of badaa to change any and everything that contradicts what they falsely attribute to their imams. Sulaiman bin Jareer, a shia scholar, after realising the falsehood of badaa, mentioned the following:
إن أئمة الرافضة وضعوا لشيعتهم مقالتين لايظهرون معهما من أئمتهم علي كذب أبدا. وهما القول بالبداء وإجازة التقية
The leaders of the Rafidah (shia) have invented two beliefs for their followers which make it impossible for people to ever detect and become aware of the lies they speak regarding their imams. They are the beliefs of badaa and taqiyyah. (Al Maqaalaat wal Firaq p. 78 and Firaq-u-Shia of al-Nawbakhti p. 64)