The first three Abrahamic religions are, of course, Judaism, Christianity and Islam. The fourth one is atheism. While it might seem atheism opposes the three other religions, it’s really a modern continuance of the three. Atheism opposes the older theistic religions in the way that Christianity opposes Judaism, and Islam opposes both of its predecessors in trying to replace them.
By atheism here I do not refer to anyone who is non-religious, but actually materialists or other people who believe in Science! as a religion, or people who see the world and life a mere biological machine. Or perhaps there is a difference between seeing life as a machines and dogmatically believing it to be so. An example of such a person would be Richard Dawkins. Someone who is not religious and does not worship any god or dogmatic system would be an atheic, whereas worshippers of materialist dogma are atheist. Notice the “ism”.
One common feature between all four Abrahamic religions is the digital, i.e. dualistic, way of thinking in the believers. Jews have a very clear sense of being the “chosen ones”, whereas the others are goyim. Christians, while claiming to believe in compassion and forgiveness, have persecuted and butchered countless people over the history for being heretics or infidels. Muslims… well, Richard Dawkins pointed it out well in a TV debate that if a Muslim commits apostasy, i.e. rejects Islam, he will be killed. Non-Muslims are naturally to be subjugated. It is as if there is a binary program in the mind of all true believers in these religions. When it detects a person to be in the same religion, he gets thumbs up. If their religion differs, it’s thumbs down. This is the basis on how you should treat others, no matter their individual accomplishments or morality.
Atheism is similar. It does not tolerate dissenters from the materialist dogma, and atheists often categorize people based on are they atheist or not. Been there, done that. At least atheists tend to be more pacifistic than the followers of less-evolved versions of their religious entity. Yet, atheism, naturally, is pure dogma without God. It eliminates the life giving feature, God, of the Abrahamic religions. While the older religions have been quite irrational and harmful in many ways, at least they understood there is something beyond the physical, something mystical. Life is more than biology, eating, shitting and fucking. There is meaning beyond human constructs. The older religions just couldn’t agree on what that meaning is (their first mistake was to think they should agree on it). Atheism takes that away. An atheist need not be violent and murderous because he is not truly alive, there is no need for him to commit violence, which is something committed by a living being against another.
Compare the Abrahamic religions to animism or polytheism. Those belief systems exude life. Everything has a spirit, or there are multiple gods, which are non-local personifications of nature in spiritual form. There is life and there is the mystical.
Atheism is merely a more or less natural evolution of the “mind-virus” of the Abrahamic religions for the modern age. We don’t believe in miracles and magic. We don’t need salvation or the kingdom of heaven. All we want is our opium and entertainment so we can wither away painlessly. But there are those who don’t see things our way, so they bother our withering. We have to get rid of them.
I am not saying that every follower of these Abrahamic religions is a nasty person, not at all. I’ve met several nice Christians, Muslims and atheists (I haven’t met many Jews, but I don’t really think they’re that different) despite their disturbing belief system. I just think their belief systems are harmful and not quite sane. I’m not a follower of Abrahamic religions, not anymore, (I was an atheist for some time), so I don’t have look at things in a binary way. I don’t have to condemn a person in total just for their beliefs.
Apostasy in Islam:Richard Dawkins extracts some truth from a Muslim: http://www.youtube.com/watch?v=pQzuFrMRA3M