All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Linguistically, the word 'Aqeedah, is derived from 'Aqd which means holding fast to something and being absolutely certain about it. In Islamic terminology, it is to believe in something with certainty. Therefore, the word 'Aqeedah indicates what a person is resolved to do, and if it corresponds with the reality, then it is a correct belief, otherwise, it is a false belief.
The correct belief is that upon which the Prophet his companions as well as the best generations which followed thereafter, were. The following proves that this is the only correct belief:
Allah Says (what means): {So if they believe in the same as you believe in, then they have been [rightly] guided.}[Quran 2:137]
Allah further Says (what means): {And the first to embrace Islam of the Muhaajiroon (those who migrated from Makkah to Madeenah) and the Ansaar (the citizens of Madeenah who helped and gave aid to the Muhaajireen) and also those who followed them exactly (in Faith). Allah is well-pleased with them as they are well-pleased with Him.}[Quran 9:100]
There are also many Ahadeeth (Prophetic narrations) as evidence to this effect. For instance, the Prophet said describing the saved group:
“They are those who adhere to what I and my companions are upon.” [At-Tirmithi]
Furthermore, the Prophet said: “The best of people are my generation and the generation who will follow them, and the generation who will follow them.” [Al-Bukhari] There are many other pieces of evidence in this regard.
To conclude, the principles of belief that Allah commands us to firmly believe in, without having any doubt about them are the belief in Allah, His Angels, His Books, His Messengers, the Last Day, and the belief in the predestination whether it is good or bad. These are the principles of belief (creed).
Thus, a Muslim is obliged to believe in everything that is reported to us from Allah and His Prophet .
Allah knows best.