Quran 49:15 – Doubt After Belief
I was referring to the kind of doubt which people have despite getting answers to their questions, and yet they choose to live in a state of doubt and not believe it. This kind of doubt has to do more with the inner struggle of a person and cannot be helped from the outside. However, any doubt when gets transformed into a question, only then it can be answered. Just saying you doubt the very foundation of religion ( Questiong Prophet Muhammad (sws) also questions the status of Quran as well ), doesn’t boat well with an informed Muslim. One can take a step back and seek answers for such doubts and then decide for himself.
Yes if you have doubt on Last Prophet Mohammed PBUH then you are not muslim. This is neccessary for all muslim for believe on Khatm e Nabwat and on Last Prophet Mohammed PBUH.