Several interesting points from reading the Institutes this morning.
First, on the difference between the god of Islam and the True God.
Calvin makes the point that God is by necessity good, meaning that God cannot choose not to be good. To get the following quote, you must understand the way a philosopher or theologian uses the word, "necessary." Something that is necessary is something that must be due to the nature of things; it cannot not be. Here's Calvin: "The goodness of God is so connected with his Godhead, that it is not more necessary to be God than to be good; . . . " As I thought on this, I realized that it forms one of the most basic distinctions between the theology of Christianity, and that of Islam.
In a word, God does good things because God, in His essence, is good. God cannot fail to be good--it is His nature to be good, and God cannot contradict Himself.
However the god of Islam is arbitrary in his actions, sometimes doing good, sometimes evil. The god of Islam is only good when he decides to be so; his actions are not tied to his essence. This is one reason why Islam can justify any atrocity: Allah is not good, Allah is just what Allah determines to be at the moment.
The second interesting point comes from Calvin's discussion of free will and the bondage produced by sin. He quotes Augustine: "Man through liberty became a sinner [speaking of the Fall] but corruption, ensuing as the penalty, has converted liberty into necessity." Calvin then says, several sentences later, "Man, since he was corrupted by the fall, sins not forced or unwilling, but voluntarily, by a most forward bias of the mind; not by violent compulsion, or external force, but by the movement of his own passion; and yet such is the depravity of his nature, that he cannot move and act except in the direction of evil." [Calvin, Institutes, Book II:3:5]
This is why we need a Savior, and this is why He must take the initiative in salvation. We won't. We can't.
