You are not to criticize. You are to stay silent.
Do you believe that there are issues with the religion of Islam? Shut up.
Do you have legitimate arguments backed up with facts that you hope Muslims will consider about their religion? Shut up.
Do you believe that Islam is a religion that institutionalizes violence and can you back your argument up with evidence from the Koran? Shut up.
That is the argument of the honor brigade, an organized campaign to silence critics of Islam. Their tactics include documenting and publicizing "slights" against the faith (Islamophobia Observatory), labeling critics as "Islamophobes" using a wide network of bloggers and pundits who attack anyone who questions Islam, and directing violence against anyone perceived as having insulted Islam. Witness Charlie Hebdo staff being murdered; Ayaan Hirsi Ali living in fear of death for having dared to leave Islam (a death sentence under the Koran, by the way) and for criticizing some practices of the religion; Theo Van Gogh, filmmaker, murdered for daring to criticize; Salman Rushdie under sentence of death for writing a book that portrayed Mohammed in a negative light; the list goes on.
The counter-argument to criticism of Islam? Shut up.
Maybe it's time that we didn't.