Quran 49:15 – Doubt After Belief
Let me ask another way. Is asking the question, as a Muslim, ‘is Muhammad صلى الله عليه وسلم really a prophet?’ Considered a doubt that would rip you of your status as a true believer?
Believe is a matter between Allah SWT and the individual. If anyone claim that he is a Muslim, nobody can call him non Muslim. In Quran Allah called the people Kuffar who refused publicly in the presence of Prophet Peace be on him, not anyone else and إِنَّ ٱللَّهَ بِكُلِّ شَىْءٍ عَلِيم If someone questions then a sincere Muslim should try to help his brother to get the answer. Best way to take him to a knowledgeable person. And then leave it to Allah and make sincere dua for him. If questioning is a problem then think about you 🙂