What is the reason for the Muslims not uniting in their enmity toward the disbelievers?

Question : The types of disbelief are multiple and varied, differing from one another, but they unite in their enmity toward Islam and its people, as if they were a single hand. We find those who claim Islam, yet they cannot unite, even in their enmity toward the disbelievers. What is the cause for the Muslims in this matter?

Answer : The cause of this, O Salim, may Allah bless you, is mentioned in the saying of Allah the Exalted: The Shaytan is extremely eager to sow enmity and hatred among the Muslims, and this happens. There is no harmony between their scholars, their callers to Allah, and their students of knowledge, so that the religion has no standing. We ask Allah to unite the hearts upon His obedience. You are lamenting the state of the Muslims, saying how the disbelievers unite against the Muslims, while the Muslims do not unite among themselves against the disbelievers. This is without doubt, and it is a source of sadness.