Distinction between Muslim and Non-Muslim

It is narrated on the authority of Abu Zubair that he heard Jabir b. ‘Abdullah saying. I heard the Messenger of Allaah (may peace and blessings be upon him) observing this: Between man and polytheism and unbelief is the abandonment of salat. (Muslim)

Lessons to learn from this Hadith

The distinction between a Muslim and a Non-Muslim is Prayer. If the person acknowledges Shahadah but does not pray, then he is a Sinful Muslim. He cannot be called a Kaafir/disbeliever. He is a sinner and not a Kaafir. But if he does not acknowledge the Shahadah and also he does not pray, then he can be a Kaafir. Hence for the reasons mentioned, this hadith cannot be taken literally. If we see a Muslim not praying, we cannot call him a Kaafir.