Muhammad had palaces, as much wives as he wanted, had all the riches, whereas Jesus always put others before him. Why would God send a greedy prophet after a kind one?
To learn, you need to think and question if the wrong things you're hearing about Islam are true, rather than just hearing a fact about Islam from a non-Muslim who doesn't know much about it, taking it as true, and then asking why did Muhammad (peace be upon him) or Jesus (peace be upon him) do xyz.
It is better if you phrase this question, as, "Is it true that Muhammad (peace be upon him) had palaces?" etc, rather than assuming that what you're hearing is true. Apart from early after his first marriage, much of his life was spent in poverty, and he was always putting others before him.
See this post:
http://www.islamicboard.com/clarifi...09951-prove-muhammad-prophet.html#post1479857
Just for your information, as Muslims, for us to refer to any prophet in derogatory terms, with adjectives such as greedy, is not allowed, and is a big sin. The prophets and messengers were the purest and noblest of humanity, known for their upright conduct and high moral characters, sent by Allah to people throughout the ages, to convey His message to them, and with guidance to show people how He wants them to live and worship Him.
Why did Jesus allow another man to die in his place?
Jesus (peace be upon him) did not allow anybody to do anything of his own volition, nor did he ever do what he had no right to - he only did what he was commanded to by God. Read the following verses from the Qur'an:
And [beware the Day] when Allah will say, "O Jesus, Son of Mary, did you say to the people, 'Take me and my mother as deities besides Allah'?" He will say, "Exalted are You! It was not for me to say that to which I have no right. If I had said it, You would have known it. You know what is within myself, and I do not know what is within Yourself. Indeed, it is You who is Knower of the unseen.
I said not to them except what You commanded me: "Worship Allah, my Lord and your Lord". And I was a witness over them as long as I was among them; but when You took me up, You were the Observer over them, and You are, over all things, Witness.
If You should punish them - indeed they are Your servants; but if You forgive them - indeed it is You who is the Exalted in Might, the Wise. (5:116-118)
You see, Jesus preached the same thing that all the messengers preached since the beginning of humanity.
To submit wholeheartedly to Allah and worship Him and Him alone, without any associates in, or parts to, His Exclusive Divinity, and to obey the prophet. They taught that people should be under no misperception that they can commit themselves to Allah as their Lord, and then combine this with accepting others as their Lord, or associating others in His Divinity, in whatever way. They taught that we should strive hard to translate our belief in the One True God into practice, by obeying Allah and the messengers He sent, who were also role models and examples for us, showing us practically how to put the guidance they were sent with into practice in our daily lives, explaining the scriptures, warning against wrong-doing, giving good tidings, and giving additional legislation from Allah.
So Islam is not a new faith, but is the same ultimate universal truth that God revealed to all the prophets, including Noah, Abraham, Moses and Jesus (peace be on them), and the same thing they all taught. Thus Islam is not named after a specific person (like Christianity, Buddhism), nor after a certain race or place (like Judaism, Hinduism), but is named by God Himself, the meaning loosely translating as 'submission to God', which is what every Prophet and their righteous followers did, from amongst all times, places and peoples. That in itself is one fraction of the evidence that it was the way of all the Prophets from the beginning.
With time, the message got forgotten or corrupted. So people started worshipping other gods along with Him, made idols, said that God begot a son, said that certain people were incarnations of God, some rejected belief in God altogether, while others elevated the status of some prophets to divine, or at the other end, rejected or blasphemed some of the prophets. Whenever God's message got distorted by people, or forgotten, a new messenger was sent, not with any new or changed message, but reinforcing the actual message that God sent all the messengers with, the actual core beliefs that people were taught from the beginning of humanity, confirming the true parts of previous teachings and scriptures, and correcting wrong beliefs and misconceptions that had crept in. God required that whenever He sent a new messenger, that messenger should be followed along with any new scripture given to him. This chain of messengers culminates in prophet Muhammad (peace on him), who is the last and final prophet and messenger. Since his prophethood, God's message is available unchanged and unadulterated, for the entire world, until the end of time. He wasn't sent as prophet and messenger for a specific group of people and specific time (e.g. as Moses and Jesus were to the Children of Israel), but he was sent for all the world, for all time, until the Day of Judgement. Thus he is the last, not first, prophet of Islam; a messenger to all mankind, for now, and for all time to come. He is the messenger who must now be followed.
Peace.
