I read this question posted on quora.com today:
“Allah can offend polytheists but no one should offend Allah and his messenger. What kind of a moral value is this?”
A valid question indeed. Did you know that Muhammad started his career as the “messenger of allah” by offending other religions? Let’s turn to the sira (the written down biography from the life of Muhammad)
When the apostle began to spread Islam among his people as Allah had commanded him, they did not gainsay him until he began to abuse their idols; but when he had done this, they accused him of seeking power, denied his revelation, and united to injure him. 
But Abu Talib, uncle of the apostle, defended him. Several nobles of the Quraysh, including Utba and Abu Sufyan, went to Abu Talib and said, ‘Your nephew has insulted our gods and condemned our religion. He considers our young men to be fools, and our fathers to have erred. You must either restrain him or allow us free action against him, since your religion is the same as ours, opposed to his.’ But the apostle continued to preach the religion of Allah and to seek conversions, and the people hated him. 
These two passages speaks about the first years of Muhammad’s prophethood (when still in Mecca, after he received his revelation). The verses tells us that Muhammad was:
1. An abuser (began to abuse their idols)
2. An insulter (has insulted our gods)
3. A condemner of other religions (condemned our religion).
Now, isn’t that ironic? Muhammad, the great example of conduct, started out his career as a prophet by insulting other religions. It’s one thing to abuse, insult and condemn, but by doing so, you should also give the same right to others. If not, you are a hypocrite.
Narrated Jabir bin ‘Abdullah:
Allah’s Apostle said, “Who is willing to kill Ka’b bin Al-Ashraf who has hurt Allah and His Apostle?” Thereupon Muhammad bin Maslama got up saying, “O Allah’s Apostle! Would you like that I kill him?” The Prophet said, “Yes,” Muhammad bin Maslama said, “Then allow me to say a (false) thing (i.e. to deceive Kab). “The Prophet said, “You may say it.” Bukhari Book 5, Volume 59, Hadith 369
By presenting before you the most trustworthy muslim sources, I have proven to you that Muhammad was a person more than willing to insult others, but refused to be treated the same way. He allowed his followers to deceive and murder his opponents. That should tell you something about his character. And the character of his religion. Think about that the next time someone gets killed for drawing a cartoon with Muhammad’s name on it.
Islam is false. Allah is a fabricated god made up by a false prophet.
 Sirat Rasoul Allah, chapter 3 “the revelation” by Ibn Ishaq