Why did Abu Sufyan oppose Islam and Prophet Muhammad?

Answer 1

Abu Sufyan and the Meccans did not oppose Muhammad arbitrarily. They had specific grievances, which included:

Preserving Religious Plurality: Abu Sufyan opposed Muhammad because 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. Muhammad 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, what Abu Sufyan did not take into account is that nearly all Arabians would convert to Islam after the fall of Mecca.

Keeping His Own Power: Abu Sufyan was one of the Chief Leaders of the Qoreish Tribe and one of the most powerful men in all of Arabia. Should Mecca fall to the Muslims, he would certainly lose substantial power. Many Muslims hold that he was corrupt as well, meaning that he stood to face criminal acts if he were subject to Muhammad's authority.

Protecting Commerce: During Muhammad's Medinan Period, Muhammad organized and executed numerous raids on caravans heading to and leaving from Mecca, causing disruption to Arabian trade routes. Since Abu Sufyan was in an important position in Mecca, this was something he would be expected to ameliorate.

Polytheism: It was likely that Abu Sufyan was fighting in defense of Arabian henotheist religion to which he ascribed against Muhammad who would demand that he abandon all gods but Allah.