Final answer:
The members of Muhammad's ummah were united by religious faith, which included the belief in one God, adherence to Muhammad's leadership, and a sense of mutual defense. They shared basic beliefs which transcended political, ethnic, and linguistic differences and were unified by Islamic law and the global Muslim community. b) Religious faith
Step-by-step explanation:
The ummah is a central concept in Islam, referring to the global community of Muslims who share a common religious identity that supersedes differences in language, ethnicity, and culture. The members of Muhammad's ummah were primarily united by religious faith, particularly the belief in one God, Muhammad's leadership, and mutual defense. This sense of unity was rooted in the teachings of Muhammad and the shared basic beliefs among all Muslims.
Despite the political fragmentation and diversity within the Islamic world, such as the existence of various Islamic empires and states, the ummah remained cohesive. This was largely due to the universal adherence to Islamic law (Sharia), and the educational, legal, and social structures that were maintained across different territories. The ulama, a class of religious clerics and scholars, played a significant role in this cohesion by engaging in scholarly debates and collaboration, thus contributing to the unity of the Muslim community through intellectual and spiritual bonds.
In conclusion, the correct answer to what united the members of Muhammad's ummah is option b: the belief in one God, Muhammad's leadership, and mutual defense.