Wa `alaykum as-salam wa rahmatullahi wa barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Brother, thanks for your interesting question and we implore Allah to guide Muslims and to give them power to resist such insults directed against Prophet Muhammad (peace and blessings be upon him). We earnestly implore Him to grant the Muslim Ummah the power to stand firm against such baseless claims in every age and place.
First of all, we would like to note that just as a defective eye may deny the sunlight, these feeble minds deny the nobleness of Muhammad (peace and blessings be upon him). It is clear that history stands as evidence on the truthfulness, the purity and the lofty morals of Muhammad (peace and blessings be upon him), who established a nation that enlightened the whole world with light and love.
In fact, there is no wonder to see lots of heretics dare to insult and attack the Messenger (peace and blessings of Allah be upon him) because they see that Muslims are careless and feel little protective jealousy towards their religion and their Prophet (peace and blessings be upon him)!
In this regard, we would like to cite for you the following fatwa issued by Dr. `Ali Juma`ah, Mufti of Egypt, in which he states the following:
Indeed, hurling insults and attacking the noble personality of the Prophet (peace and blessings be upon him) by non-Muslims is nothing new. Rather it is an often repeated scenario. I would like to stress that such insults against the Prophet (peace and blessings be upon him) do stress his high status and noble characterů
Although we categorically deny the perverted behavior of those ill-mannered people who attack the Prophet (peace and blessings be upon him) and insult him, we are ordered to call people to the truth with wisdom and fair exhortation.
Indeed, the enemies of Islam hurl insults and attacks not only on the Prophet (peace and blessings be upon him), but also on their own prophets and messengers. For example, Prophet Moses was insulted in a film directed by one of those avowed enemies, and so was Prophet Jesus (peace and blessings be upon them all).
Finally, I would like to state that the enemies of Islam will continue in their campaign of attacks and insults, especially against Prophet Muhammad (peace and blessings be upon him), and we Muslims warn them against their erroneous approach and the unjust trend they are embarking on!