The Prophet (peace and blessings of Allaah be upon him) said: “My ummah will split into seventy-three sects, all of whom will be in Hell except one group.” Sahaba said: “Who are they, O Messenger of Allaah? He said: “(Those who follow) that which I and my companions follow.”
The ‘Aqeedah is the most important of affairs. The Prophet (sallallaahu alayhi wasallam) was in Mecca for thirteen years, and all of that time was given to the Aqeedah. The Aqeedah is the foundation of the Religion.