Why was Muhammad's faith questioned?

Answer 1

Answer 1

Well because all the different religions going around.

Answer 2

There were several reasons that people opposed Mohammed and his faith.

Preserving Religious Pluralism: The religious plurality permitted in Mecca was critical for maintaining Mecca's important position along the Arabian trade routes. It was on account of the fact that Mecca was holy site for all Arabian faiths that spared it from internal conflict and allowed the flourishing of commerce in the city. Mohammed made clear that he intended to purge the idols from the Kaaba which would cause mass uproar and ended Mecca's position as a holy site for all Arabians. Of course, this does not take into account is that nearly all Arabians would convert to Islam after the fall of Mecca.

Politics: The Chief Leaders of the Qoreish Tribe were the most powerful men in all of Arabia. Should Mecca fall to the Muslims, they would certainly lose substantial power. Since Muslims believed that these leaders were corrupt, they likely stood to face criminal acts if they were subject to Mohammed's authority.

Commerce: During Mohammed's Medinan Period, Mohammed organized and executed numerous raids on caravans heading to and leaving from Mecca, causing disruption to Arabian trade routes. Violently attacking peaceful convoys does not speak well of your faith/group.

Polytheism: Mohammed demanded that all polytheists abandon their gods for the singular Allah. Polytheists were incensed that they should have to conform to Mohammed's standards.

Incongruities with Other Monotheisms: Many Jews and Christians saw the revelations of the Qur'an to be bits and pieces from their traditional scriptures and religious commentaries. They felt like Mohammed was repackaging their traditions and doing so incorrectly as a result, they saw no reason to convert to Islam.

Massacres of Opponents: Mohammed massacred tribes (most often Jewish tribes, but polytheist tribes as well) that did not align themselves with him in war. Regardless of whether this was permissible, which most historians say was a valid 7th century tactic, it did not engender warm feelings between the massacred and Mohammed.