the quran and non-violence

Whenever the issue of Islam and non-violence and Islam comes up, I almost always think about how the Quran describes the story of Cain and Abel, and how it differs from the Bible's account. Reading the Bible, I got the impression that Cain basically snuck up on Abel and hit him upside the head with a big rock. But in the Quran, it is described as follows:

[5.27] And relate to them the story of the two sons of Adam with truth when they both offered an offering, but it was accepted from one of them and was not accepted from the other. He said: I I will most certainly slay you. (The other) said: Allah only accepts from those who guard (against evil).
[5.28] If you will stretch forth your hand towards me to slay me, I am not one to stretch forth my hand towards you to slay you surely I fear Allah, the Lord of the worlds:
[5.29] Surely I wish that you should bear the sin committed against me and your own sin, and so you would be of the inmates of the fire, and this is the recompense of the unjust.
[5.30] Then his mind facilitated to him the slaying of his brother so he slew him; then he became one of the losers

So instead of being surprised by Cain, Abel totally sees it coming and chooses not to kill his brother. This is not to say that Islam insists on pacifism (it obviously doesn't). Islam teaches that in this violent unjust world, sometimes aggression needs to be held in check by force. But what the above shows is that within the Quran there are also examples of non-violent resistance.