Materialist,
I hope your inquiry is sincere because I'll give you a sincere answer. In Islamic Eschatology (Study of Apocalypse) hell does exist and yes, you are tormented there. But let me clarify two things for you:
1) The duration of Hell
2) The physicality of Hell
1) The reason Hell is "eternal" is because in the next life (or the world to come) there is no concept of time. Since there is no concept of time the events endure thus becoming an infinite event. Because Hell is all one event all that is done there is endless. In similar fashion, Christians (and some Jewish thought) have a similar idea of Hell where the wicked endure pain for all eternity.
2) Hell is described physically because it is more done on the basis of giving the believers an idea of how dreadful it is. According to Islamic theology, the dead will be raised up both body and soul to God where all will be judged accordingly. Perhaps this explains why we get the sensation of pain and pleasure in the next worlds. According to the Qur'an Heaven is an endless pleasure but in contrast to this so will Hell be an endless torment.
Why is there no moral outrage?
Because as Muslims, we define our morality on the basis of what God has established in Islam. Of course, I may share differing views on certain ethical situations but for the most part, what Muslims believe in morality is on par with the rest of the world. Feed the poor. Help the helpless. Do good works. Do not be excessive in actions. Be good to your mate. Study the world so you may recognize divine providence. Now let me say that of course other Muslims may have differing views on this so do not think my opinion alone is unanimous. But understand here that for Muslims, when one non-Muslim becomes cognizant of Muhammad (with proper education on Islam by the way) then that individual is in the sense, obligated to either choose or not choose Islam. Of course there is a choice in reality however that choice can also have repricussion.
Some school of thought say that the non-muslim that is properly educated on Muhammad and his message will be questioned by God on the Day of Judgement and will go to hell despite what he or she has done in the real life. The other school of thought holds that God will question the non-muslim on his/her rejection of Muhammad but will consider their good works and may determine that this individual will be in Hell for a short time. Another school of thought holds God may not send that individual to Hell at all. But in essence to all of this what they all equal to is God making the ultimate decision. There is no moral outrage because God ultimately decides all of this. The main essence to Islamic ethics starts with God and ends with us.
As far as what type of transgression we could do that lands us in Hell is Shirk or associating other dieties aside with God (or replacing God with them). Now mind you there are several schools of thought concerning Shirk which has several long interpretations I don't want to get into.
In my personal opinion being away from God the Creator is hell and no amount of fire or torment is greater than that. To me hell is like being trapped in a dark room with no light. In some sense I believe Hell is metaphircal to represent the pain and agony of being away from God not the literal but who knows? I hope I was some help Materialist.