"Aspirations of world conquest? Have you seen Jewish and Christian scripture? Or most religions, in fact?"
You are ignorant. Hindu, Taoist and Buddhist scripture say nothing about world conquest, and you are making a huge false equivalence to lump them all in together. Jewish and Christian scripture speak of a time after Time, when the Messiah will come and all kingdoms will submit to Him. That is not a call for world conquest in the here and now. Islam divides the world into that which is already the House of Islam, and that which is the House of War aka the part that Islam hasn't conquered yet.
"At least Islam has some level of official protection of non-combatants of other religions"
This is laughable. Try to be a Christian in Saudi Arabia. Which nations show respect and tolerance for a diversity of religions? Not the Muslim ones.
"Death cult? Pretty much any religion that believes in life after death, or anything like it, can be classed as a death cult, since it discourages fear of death."
Perhaps, but which religion's adherents glorify their young children going and blowing themselves up? Which promises glory and reward for the murdering others with your martyrdom. This is a key distinction. Christianity celebrates martyrs, but they are suffering martyrs. They are the persecuted and the oppressed. Islam celebrates those who kill the infidel when they die.
"Islam does not attack those who leave the faith"
Absolutely false. There are plenty of examples of converts who left Islam being killed, shunned, or otherwise punished by their families and their societies.
"is a lot more liberal about other religions in theory than most others"
See above. There is no actual evidence of this, no matter what the theory is.
"nihilism is nowhere to be found in the Koran"
Nihilism may not be the right word. But a certain pessimism and ennui is the result of the doctrine of Inshallah, that is "if Allah wills." Nothing that happens is against the will of Allah. Nothing can be done that is against Allah's will. So if society sucks, must be Allah's will. If I killed your friend, it was Allah's will. If my daughter is sentenced to death for having been raped, it was Allah's will. That is immoral.
"totalitarianism is prevalent in a lot of religions, since religion holds power over people"
Islam is a complete legal and political system, in a way that makes it more a doctrine of statecraft than a religion. Christianity emphasizes a kingdom that is not of this world, and tells us to "Render to Caesar." In the ideal Islamic state, the Caliph would also be the head of the faith.
"it is no more dehumanizing than almost every religion I've seen"
Islam means submission. It is a religion of obedience. There is no thought, there is no struggle, there is only submission. People are the slaves of Allah. In Christianity, on the other hand, we are invited to be God's friends and His children. It is a religion of love, and it is a religion of reason. God is expected to act upon principles which we can understand. In Islam, Allah does what he wants, and we just have to accept it.
"As for mocking of Judaism or Christianity, I don't see grounds for any objections to doing so. Either the moral integrity of the faith will get it through the mocking unharmed, or it deserves to be mocked."
People can mock all they want. What I find fascinating and troubling is that the most anti-liberal of religions, Islam, which is anti-woman, anti-gay, anti-free speech, and in every other way contrary to those values liberals claim to respect, is constantly defended by liberals. Every now and then a Bill Maher or a Richard Dawkins will get it.