God told me to do it

This morning I read Genesis 22. This is one of those parts of the Bible (especially the Old Testament) that terrify me; make me scared of the God I worship.

Here, God commands Abraham to kill his son:

Then God said, "Take your son, your only son, Isaac, whom you love, and go to the region of Moriah. Sacrifice him there as a burnt offering on one of the mountains I will tell you about." Genesis 22:2

Abraham, full of faith in his God, obeys:

When they reached the place God had told him about, Abraham built an altar there and arranged the wood on it. He bound his son Isaac and laid him on the altar, on top of the wood. Then he reached out his hand and took the knife to slay his son. Genesis 22:9-10

Luckily, God stops Abraham at the last moment, as if to say "Just kidding! Good, job, you were actually going to do that, weren't you!"

But the angel of the LORD called out to him from heaven, "Abraham! Abraham!""Here I am," he replied."Do not lay a hand on the boy," he said. "Do not do anything to him. Now I know that you fear God, because you have not withheld from me your son, your only son." Genesis 22:11-12

What are we supposed to think of this? Would I be able to obey God in this way? I think Abraham is lucky that God was speaking to him in actual audible words. How can you say no when God's voice is booming through the air, commanding you do do something, even if that thing is absolutely horrible?

Today, we are not so lucky. Today we have the Holy Spirit, (which of course wasn't available to Abraham) who is a little more subtle in His communication. The Holy Spirit seems to speak to us mainly though our circumstances, the Bible, and of course through voices in our heads. But this raises lots of questions:

How would I know if God was telling me to kill my son? What if a little voice in my head started telling me to kill my son? Should I obey? If someone I know told me they were going to kill their child because God told them to do it, should I consider them a "pillar of faith" or a psycho?

Is God going to ask me to do something or believe something that is completely insane? What if he asks me to believe the universe is younger than some trees that are still alive today?

Might Satan communicate with us in much the same ways? It seems likely that killing a child might be something he might really enjoy watching me carry out. He might also enjoy the confusion and doubt that comes from holding to a "scientific" belief that is not supported by any evidence.

Isn't it against the nature of God to command us to sin? I know the sixth commandment wasn't given to Moses until a few hundred years later, but does that make murder okay in Abraham's day? I doubt it. Of course, God surely knew Abraham would not have to go through with His command, but this does not change Abraham's perception of the event.

Is God this cruel? Was this just a really extreme test for Abraham, because he was really important? A kind of "stress test" to put Abraham through before he built a nation on him?

I could write questions all day.