The prophet Mohammed erred. The Koran, which allegedly Mohammed received as a message from God, describes Jesus' birth as a virgin birth, that is, Jesus' mother Mary had, in the words of one English translation of the Koran, "neither been touched by any man nor ever been unchaste" (19:19).
Jesus was not born of a virgin. Although biologists know that virginal births are a very rare possibility, such births would almost invariably result in a girl and never a boy because the man contributes the Y chromosome that distinguishes males from females. Over the last couple of centuries, Christians have helpfully moved from reading scripture literally to reading it metaphorically. The story of the virgin birth is significant because of what the gospel authors want to say about their experience of Jesus and not because the authors are making a biological claim.
Muslims extremists have not made a similar shift, but still read their scripture literally. In other words, they believe Jesus was born of a virgin because both that is what they read in the Koran and Mohammed accurately recited what God had spoken to him.
Either God lied (I find the notion of God intentionally deceiving anyone ludicrous) or Mohammed got it wrong. Jesus was not born of a virgin.
Am I, like the Charlie Hebdo satirical cartoonists, disrespecting Mohammed and Islam? Alternatively, am I expressing an opinion based upon analyzing a text in light of scientific information?
Ideally, individuals express their ideas in ways that are respectful of others. However, respect for others that precludes an open, honest exchange of views is in fact insulting of others. It's naïve to imagine that everyone agrees about anything. Differences of opinion and value are endemic to the human condition. I know that some Muslims will disagree with my conclusion that Mohammed erred; some Christians similarly continue to cling to the anachronistic notion of a virgin birth.
Stifling public discourse by insisting that persons only say that to which nobody will take offense is equivalent to completely ending public discourse. Adversarial legal systems exist, in part, because communities have recognized that the best approach to discerning true from false is to encourage open debate. Admittedly, the process often results in partial truths or even upholding falsehoods. Nevertheless, open debate, in which we weigh evidence and arguments and test hypotheses, generally yields the most progress in science, law, and religion.
My hope is that in time, both Muslims and Christians completely abandon the rigid fundamentalism that leads to hatred, enmity, and violence because they find it so unbelievable in view of everything else that they know about the world. Until then, refraining from voicing about controversial opinions to avoid giving offense or out of concern for one's own safety allows extremism to continue unchecked.