While reading Wikipedia today, i discovered: The Satanic Verses controversy.
In summary: A guy (Salman Rushdie) wrote a novel “Satanic Verses” (1988) that was considered blasphemous by the Islamics. A Islamics leader (Ruhollah Khomeini) issued a edict for Muslims to kill the author and publisher or others involved, as in accordance to Islam's scripture. This edict is widely and openly echoed in islamic communities, even in many countries a vow to murder is illegal. The author lived under government (UK) protection in hiding over a decade. One translator (Hitoshi Igarashi) of the book got murdered and some bookstore are bombed (others were attempted). UK severed diplomatic relation with Persian (Iran) over this incident…
The Abrahamic religions (i.e. Judaism, Christianity, Islam) are aggressive in controlling its member's thoughts and in growing itself. For example, prayer before meal is a requirement in most of these religions. It is a fundamental brain-washing technique at work. Because, eating is the most important activity in a human animal. In a sense, the edict tries to associate eating with the sect.
As a example of Abrahamic sect's aggression, they often have a law that promotes the killing or destruction of any activities of outsiders that may harm the sect. Such activity, is termed sacrilegious or blasphemy, by the sect's leaders (priests). So, in a society predominated by these sect's members, (e.g. USA, some Europe, Middle East, South America), it is immoral or even illegal, to make statements or activities that are deemed harmful to the sect, while it is legal or even considered moral, for these sect's to trample all over non-religious people. As a concrete example, in the modern day, when atheist stating their beliefs on issues like God or the Bible, they must be careful and express it in a twisted way as to not “offend” or be “blasphemous” to these sects. However, when these sect's leaders or officers (pope, bishop, priest, missionaries, ministries etc) go about spreading their sect's propaganda such as God and commandments (sect's law), they have little to worry about atheists. (However, each of them has to worry about each other in their business. e.g. Christians vs Islam, even sub-factions such as when Mormons express their fine points about Bible, Jesus, or God, they have to watch out for Catholics, Protestants, etc, and vice versa.)
The asymmetry of Abrahamic sects's freedom in saying what they want to say without regards to atheists, is because, atheism, isn't a organized sect to begin with. It is simply a grouping term, while each of the Christian, Islam, (and Judaism?) are de facto sects with huge organizations, structure, members, schools, orders, laws, and actually militaries and campaigns.
If atheism, also historically developed into a organized sect, with its own scriptures (or, holy principles), leaders, ranks, posts, schools, militaries, and campaigns, then it may become in some sense respectable. And in a society with large number of such sect's member, that any speech or expression that may considered harmful to atheist's point of view, will be regarded improper, immoral or illegal. (i.e. blasphemies)
The question now may be, why did those Abrahamic sects developed in history, while atheists didn't develop into a organized religion? I think the answer is rather simple. In eras without science, primitive thoughts such as superstition, ghosts, souls, deities, curses are the normal forms of thinking. Human animals (male), even in primitive era, engage in power struggle with each other, from brother fights to leadership ascension to tribal wars. Spirituality or those mystic and un-explained, easily becomes the binding force for groups. Atheism as a concept cannot develop without the background of science (Atheism cannot thrive in a community with high-superstition, supernatural beliefs, mysticism). Among the factions, the aggressive camps, those power hungry, intolerant, and exclusive ones, become the Abrahamic sects as we know today.
It is interesting that today, in modern society, a few has tried to developed atheism into a organized sect. Notable is the Church of Satan by Anton Szandor LaVey (1930 〜 1997).
In the current decade's communication revolution age, the society is changing rapidly. The masses in developed countries (USA, Canada, much of Europe) are increasingly secular. The best way to spread atheism may not be to join the Church of Satan, but simply keep all the communication, the exchanging of info, going.
(Note: Some communist states, such as Russia and in particular China, can be considered as modern development of organized atheism.)