• The extraordinary events on the night of his birth, the different character he displayed even as a child, and the meaningful signs people of insight observed on him all meant that he would undertake a great mission. 
• Prior to his Prophethood, he opposed injustice and joined organizations like the Hilf al-Fudul, which defended the helpless and restored usurped rights.
• Although of honorable descent, he did not live in luxury; rather, he grew up as an orphan under the protection of his grandfather and then his uncle. Whatever money he may have earned by trading before and after his marriage went to support orphans, widows, and the poor. Thus, he was never wealthy and had no powerful backers.
• Despite his community's moral corruption, he lived an extraordinarily chaste, disciplined, and morally upright life. During his childhood, he intended only twice to attend wedding ceremonies, but was overpowered by sleep on both occasions. (Thus, he did not see improper things and practices that Islam would later outlaw.) When he was 25 years old, he married Khadija, a respected 40-year old widow. He only married again after her death 25 years later. Those who knew him said he was as shy as a young girl when asked for in marriage.
• Muhammad's childhood and youth were a prelude to his Prophethood. Even his enemies called him "the Trustworthy," for no one could deny that he was completely truthful and trustworthy. People said: "If you travel, you can entrust your family and belongings to Muhammad without hesitation." Once while the Quraysh were repairing the Ka'ba, a question of individual and clan honor arose over who would reinsert the sacred Black Stone. To prevent violence, they all agreed to let Muhammad decide. He asked them to bring a piece of cloth, which he then spread on the ground. Placing the Black Stone on it, he told each chief to raise their corner. When the Black Stone was raised to the required height, he set it in its place.
• Muhammad was unlettered. During his whole life, no one taught him and no written culture influenced him. Toward his fortieth year, he began retreating to Hira cave. One day he emerged with a new, wholly authentic message to heal humanity's wounds, and challenged all literary geniuses to produce something like it.
• His enemies never accused him of lying or cheating. To prevent Islam's spread, they labeled him a poet, a sorcerer a magician, or a lunatic. Sometimes they attempted to justify their rejection by such false pretexts as: "If only this Qur'an had been sent down to one of the great men of the two cities (Makka and Ta'if)."
• How could a 40-year-old man, universally acclaimed by his society as completely honest and trustworthy, one who had no moral and intellectual imperfection, suddenly and unexpectedly begin to lie and deceive his people without ever being caught? Even enemies who had known him for years never accused him of this. They never caught him in a lie, could not meet his challenge to produce a similar document, and could not discredit him. After years of warfare driven by base motives, even his bitterest enemies (e.g., Safwan ibn Umayya, Abu Sufyan ibn Harb, 'Amr ibn al-'As, and Ikrima ibn Abi Jahl) finally accepted the truth of his message.
When he was entrusted with the duty of Prophethood, his life did not change at all. There are also several other points to consider:
• If Prophet Muhammad, upon him be peace and blessings, nursed selfish aims and intentions, why did he wait until he was 40 to claim Prophethood?
• Until he was 40, no one had ever heard Muhammad give an eloquent speech, talk on religious and metaphysical issues, formulate laws, or handle a sword. How could he have changed so suddenly from a reserved, quiet, and completely apolitical man into the greatest reformer history has ever known? He explains intricate metaphysical and theological problems, why nations decline and fall, and ethical canons; gives laws related to social culture, economic organization, group conduct, and international relations; and becomes so brave that he never retreats in battle. He changed his people's modes of thought, worldviews, beliefs, habits, and morals.
• Prophet Muhammad, upon him be peace and blessings, blended many roles and his own personal excellences into one personality. He is a man of wisdom and foresight, a living embodiment of his own teachings; a great statesman and military genius; a legislator and teacher of morals; a spiritual luminary and religious guide. He sees life comprehensively, and all that he touches is improved and adorned. His teachings regulate everything from international relations to eating, drinking, sleeping, and personal hygiene. He used these teachings to establish a civilization and a culture that produced such a fine, sensitive, and perfect equilibrium in all aspects of life that no trace of a flaw, deficiency, or incompleteness has ever been found in it. What alleged shortcomings and imperfections deny him his rightful status of Prophet and Messenger of God?
• Muhammad, upon him be peace and blessings, lived as the poorest of his community. All of his resources were used to spread Islam. Despite his greatness, he presented himself as the humblest and most ordinary person. He sought no material reward or profit, left no property for his heirs, and ordered his followers not to set something aside for himself or his descendants. In fact, he forbade his family and progeny from receiving zakat (alms).
• Muhammad, upon him be peace and blessings, was extremely merciful. In Makka, persistent persecution eventually forced him to emigrate to Madina. However, when he finally conquered Makka without bloodshed after 5 years of warfare, he forgave all of his enemies, including the Hypocrites and unbelievers. He knew who the Hypocrites were, but concealed their identities so they could enjoy the rights of full citizenship to which their outward confession of faith and practice entitled them.
• Prophet Muhammad, upon him be peace and blessings, was particularly fond of children. Whenever he saw a child crying, he would sit beside him or her and share his or her feelings. He felt a mother's pain for her child more than the mother herself. Once he said: "I stand in prayer and wish to prolong it. However, I hear a child cry and shorten the prayer for the sake of its mother, who is praying in the congregation." He took children in arms and hugged them, sometimes carrying them on his shoulders. As for animals, he once said that a prostitute was guided to truth by God and ultimately went to Paradise for giving water to a dog dying of thirst, while another woman was condemned to Hell for letting a cat starve to death.
• Prophet Muhammad, upon him be peace and blessings, was extremely mild and never took anything personally. When people slandered his wife 'A'isha, may God be pleased with her, he did not punish them after she was cleared. Bedouins often came to his presence and behaved impolitely; he did not even frown at them.
• He was the most generous of people, and liked to distribute whatever he had. After Prophethood had been bestowed upon him, he and his wealthy wife Khadija spent all they had in the way of God. When Khadija, may God be pleased with her, died, they were so poor that he had to borrow money to buy a shroud in which to bury the first person to embrace Islam and his first supporter.
According to the Prophet, this world is like a tree whose shade is enjoyed by people on a long journey. No one lives forever, so people must prepare for the journey's second part: Paradise or Hell. His mission was to guide people to truth by all permissible means, which he did. Once 'Umar saw him lying on a rough mat and wept, saying:
O Messenger of God! While kings sleep in soft feather beds, you lie on a rough mat. You are the Messenger of God and therefore deserve more than any other people an easy life. The Messenger answered him: Do you not agree that [the luxuries of] the world be theirs but those of the Hereafter ours?
Islam does not approve of a monastic life. It came to secure justice and humanity's well-being, and warns people against over-indulgence. For this reason, many Muslims chose an ascetic life. Although Muslims generally became rich after the death of the Messenger, upon him be peace and blessings, Caliphs Abu Bakr, 'Umar, and 'Ali preferred austerity partly because of their own inclination and partly to follow the Prophet's example strictly. Many other Muslims made this same choice.
• Prophet Muhammad, upon him be peace and blessings, was the most modest person. As he attained higher ranks, he increased in humility and servanthood to God. He preferred being a Prophet-slave to being a Prophet-king. While building the mosque in Madina, he carried two sun-dried bricks while everybody else carried one. While digging the ditch around Madina to defend it during the Battle of the Ditch, the Companions bound a stone around their bellies because of hunger; the Messenger bound two. When a man began to tremble because of his aweinspiring appearance, the Messenger calmed him, saying: "Don't be afraid, brother. I am a man, like you, whose mother used to eat dry bread." A mentally unbalanced woman once pulled him by the hand and said: "Come with me and do my housework." God's Messenger, upon him be peace and blessings, did as she asked. 'A'isha said the Messenger patched his clothes, repaired his shoes, and helped his wives with the housework.
'Ali, may God be pleased with him, describes the Prophet, upon him be peace and blessings, as follows:
God's Messenger was the most generous of people in giving out and the mildest and foremost of them in patience and perseverance. He was the most truthful of people in speech, the most amiable and congenial in companionship and the noblest of them in family. Whoever sees him first is stricken by awe of him but whoever knows him closely is attracted to him deeply, and whoever attempts to describe him says: "I have, either before him or after him, never seen the like of him, upon him be peace and blessings."
Other than conveying God's Message by performing the mission of Divine Messengership, who led such an austere life as Muhammad, upon him be peace and blessings? How can he be other than a Prophet? What substantial argument can one put forward against his Prophethood?