Christians also believe that God is love (1 John 4:8). Let's take a moment to ponder what this claim might mean in relation to His role as creator.
Plato/Socrates pondered the question "Is good good because the gods love it or do the gods love it because it is good." The implicit answer I perceive most Christians to take--and the answer most popular among Christian philosophers and ethicists seems to fall into the category of "God loves good because it is good." Those who take this position would probably not word it this way, but it is how I would categorize their position.
What I mean is that Christians tend to predicate goodness of God's "nature," as something He could not be anything but. The opposing idea is known as "Divine Command Theory." This is the idea that anything God commands is good, even if he were to command someone to offer his only son as a sacrifice (:-)
I have problems with the idea that God loves the good because it is good or because it is His essential nature. For one thing, I'm not sure what this means. Good is a ultimately an adjective when it comes to concrete reality. Only as an abstract concept is it a noun. Are we then saying that God only does "good" things?
But what are good things? A child would say they are things that bring pleasure, while something is bad if it brings pain. Adults come to speak of the "greater good." One person might say these are goods that ultimately bring greater happiness in the philosophical sense (eudaimonia). However, pain may be involved on the way to that greater good.
Talk of a "moral structure" to the universe seems equally ambiguous to me. Even C. S. Lewis reduced such a structure to the fact that people everywhere have a sense of right and wrong, not to a specific list. Indeed, it is very difficult to find a core list of morals accepted by all cultures everywhere. Perhaps all healthy cultures have a sense that it is wrong to kill certain "innocents," although such innocents are variously designated.
Finally, something inside of me wants to say that God could create a universe where the things we think of as bad are good and the things we think of as good are bad. This is not that universe, but there is a part of me that hesitates to venture anything about God's "nature" in anything but a sense relative to this universe. This approach places God beyond our universe in mystery, as it would seem a true God should be--not something our minds can tame and grasp in neat systems of philosophical-theological thought.
Also, I want to allow God to do things that would be evil for me to do even within this universe. The most famous example is God's command to Abraham to sacrifice Isaac. Somehow it seems a cop-out to me to suggest that God was just testing Abraham, that God could never have let Abraham go through with it. I want to say that God sets the rules, He commands and thus defines what is "good."
Nevertheless, I believe that He has defined "good" as love in this universe, where love is both the attitude and the act of benefiting others. He has done this particularly through Christian revelation but also partially through creation. Good thus does involve on a basic level working toward the greatest possible happiness and pleasure of others.
By faith I believe God chooses to operate by His own rules in this universe--that He operates toward the greater happiness and ultimately pleasure of all. But God alone is allowed to violate His own rules--by definition any such action will be good if He does it. Also, His "nature" as love must be balanced with another representation of His "nature" in this universe, namely, His justice...