Through revelation from God (Allah), Muhammad (Peace be upon him) transferred humanity from obedience and submission to other men to the worship and submission to God alone, associating nothing with Him. Consequently, humankind became free from servitude to other than Allah, and this is the greatest honor for mankind.
Through revelation from God, Muhammad (Peace be upon him) liberated the human mind from superstition, deception, and submission to false objects of worship as well as those concepts contrary to reason, such as the claim that God had a human son whom He sacrificed to atone for the sins of humanity.
Muhammad (Peace be upon him) laid the foundations for tolerance among people. In the Qur'an, Allah revealed to His Prophet that there is to be no compulsion in the acceptance of religion. Muhammad (Peace be upon him) also clarified the rights of the non-Muslims who do not wage war against Muslims and guaranteed protection of their lives, children, property and honor. Even today in many Muslim countries there are Jewish and Christian citizens living in peace and security in contrast to the Spanish Inquisitions in which Muslims were exterminated in an ethnic cleansing that violated all the humanitarian principles asserted by the western culture.
Muhammad (Peace be upon him) was a mercy sent by God to all peoples regardless of race or faith. In fact, his teachings include mercy even to birds and animals, and forbid harming them without right or reason.
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source: islamkingdom