Muhammad (peace be upon him) taught many important principles and morals, and even set forth rules for combat setting the precedent and still exceeding the rules of war set forth by the Geneva convention.
Consider the following:
All innocent life was sacred and as such none could be harmed, except those who were engaged against them in active combat. Saving one life was as if one had saved the entire world, while taking an innocent life was as if one had taken the lives of the entire world.
There was to be no genocide of any tribes even up until some had committed genocide against some Muslims. He offered mutual protection and forgiveness to the all even after certain ones broke their covenants with him many times. He did not allow them to be attacked until it was clearly proven they were traitors during time of war and tried to bring down the Prophet (peace be upon him) and the Muslims at any cost. Retaliation was only to those jews who had turned traitor and not others.
Slaves were common in those days for all nations and tribes. It was Islam that encouraged freeing of the slaves and the great reward from allah for those who did so. Prophet (peace be upon him) gave the example of this by freeing slaves and encouraging all of his followers to do the same. examples include his own servant (who was actually considered like a son to him) Zaid Ibn Al Haritha and Bilal the slave who was bought by Abu Bakr only for the purpose of freeing him.
While there were many attempts of assassination made on Muhammad (peace be upon him) (most famous was the night that ali took his place in bed while he and Abu Bakr escaped to Madinah), he did not allow his companions to slaughter any of those who had been involved in these attempts. Proof for this is when they entered Makkah triumphantly and his first words were to command his followers not to harm such and such tribes and so and so families. This was one of the most famous of his acts of forgiveness and humbleness.
Military combat was forbidden for the first thirteen years of Prophet hood. The desert Arabs did not need anyone to tell them how to fight or do combat. They were experts in this area and held feuds amongst tribes that lasted for decades. It was not until the proper method of warfare was instituted by Allah in the Quran, with proper rights and limitations according his commandments, that any retaliation or combat was sanctioned. Orders from Allah made it clear who was to be attacked, how and when and to what extent fighting could take place.
Destruction of infrastructures is absolutely forbidden except when it is ordained by Allah in certain instances and then only according to his commands.
Cursing and invoking evil actually came to the prophet (peace be upon him) from his enemies, while he would be praying for their guidance. Classic example is that of his journey to At-Taif where the leaders would not even hear him out nor offer so much as the normal courtesy called for and instead they set the children of the street against him, throwing rocks and stones at him until his body was bleeding so much, blood filled his sandals. He was offered revenge by the angel gabriel, if he would give the command, Allah would cause the surrounding mountains to fall down upon them destroying them all. instead of cursing them or asking for their destruction, he prayed for them to be guided to worship their lord alone, without any partners.
Prophet Muhammad (peace be upon him) claimed every person who is born is born in a state of Islam (submission to god on his terms in peace), as a Muslim (mu-islam means; "one who does Islam" i.e.; submits to god's will and obeys his commandments). he further stated, god has created each person in the image that is his according to his plan, and their spirit is his. Then as they grow older they begin to distort their faith according to the influence of the prevailing society and their own prejudices.
Muhammad (peace be upon him) taught his followers to believe in the God of Adam, Noah, Abraham, Jacob, Moses, David, Solomon and Jesus, peace be upon them all, and to believe in them as true Prophets, Messengers and servants of almighty Allah. He insisted on ranking all the Prophets up at the highest level without any distinction between them, and ordered his followers to say the words, "peace be upon him" after mentioning their names.
He also taught the torah (old testament), Zabur (psalms) and Enjil (gospel or new testament) were originally from the very same source as the quran, from allah to the angel gabriel. he asked the jews to judge according to their own book, and they tried to cover up some of it to hide the correct judgment, knowing he (peace be upon him) could not read.
He prophesied, predicted and foretold of events to come and they happened just as he had said they would. He mentioned so many things that people of his time could not have known, yet we have seen the evidences manifest over and over throughout the centuries in science, medicine, biology, embryology, psychology, metrology, geology and many other disciplines and even space travel and wireless communications, all of which we take for granted today. He even predicted something from the past that would come true in the future, and it has..
The Quran states Pharaoh was drowned in the red sea while chasing after Moses and Allah said he would preserve Pharaoh as a sign for the future. Dr. Maurice bucaille in his book, "bible, quran and science" makes it clear this has happened and the very person of Pharaoh has been discovered in egypt and is now on display for all to see.
This event took place thousands of years before Muhammad (peace be upon him) and it came true in the last few decades, many centuries after his death.
Muhammad (peace be upon him) or his followers never at any time claimed that he was a son of god or the god-incarnate or a man with divinity – but he always was and is even today considered as only a Messenger chosen by God. He insisted people praise almighty God, alone and not to celebrate him or his companions in any way. while most people do not hesitate to raise to divinity and even make 'Gods' out of other individuals whose lives and missions have been lost in legend. historically speaking, none of these legends achieved even a fraction of what Muhammad (peace be upon him) accomplished.
Uniting mankind together for the purpose of worshipping the one God of Adam and all the other prophets, peace be upon them all, was his main motivating cause and his striving was for the sole purpose having everyone to understand and follow the codes of moral excellence set forth by allah in his revelations.
Today after a lapse of fourteen centuries, the life and teachings of Muhammad (peace be upon him) have survived without the slightest loss, alteration or interpolation. They offer the same undying hope for treating mankind's many ills, which they did when he was alive. This is not a claim of Muhammad’s (peace be upon him) followers, but the inescapable conclusion forced upon by a critical and unbiased history.
Muhammad (peace be upon him) claimed to be a servant, Messenger and Prophet of the almighty God; the same God of Adam, Abraham, Moses, David and Solomon and of Jesus, the Christ, son of Mary (peace be upon them all). He claimed he was receiving revelation from almighty God (Allah) through the arch angel Gabriel, calling it the recitation (Quran).
He ordered people to believe in God as one, without partners, and to follow the commandments of almighty God to the best of their abilities.
He forbade himself and his followers from evil practices and filthy habits, showing them the proper ways to eat, drink, use the toilet and proper behavior in all relationships. this he claimed was all from Allah.