Question:
What is the criteria laid for AQEEDAH: is aqeedah the differentiator between a Muslim and kafir, and if one does not consider the world of grave as reality what is the ruling on that person because he thinks that its not 100% sure?
Answer:
The differentiator is that whoever unambiguously denies an aspect of the Religion that is obligatorily known – e.g. denying the fact that praying five times a day is obligatory – is considered a disbeliever. One who does not consider the life in the grave a reality is a Mu`tazili, and/or Shi`i, and/or belonging to one of the philosophical or other multifarious non-Sunni sects in Islam whose belief varies from bid`a to kufr although on that very point they are considered Muslim.
Hajj Gibril