"There was one who was great by virtue of his power, one who was great by virtue of his wisdom, one who was great by virtue of his hope, and one who was great by virtue of his love.
"But Abraham was greater than these: great by virtue of power which is impotence, great by virtue of wisdom whose secret is foolishness, great by virtue of hope that takes the form of madness, and great by virtue of a love which is hatred of oneself." -- Of Fear and Trembling (my favorite quote by my favorite translator)
Abraham is described as a man who could do no other than the will of God. He takes Isaac up on Mt. Moriah, builds an alter as Isaac watches and then ties Isaac down and draws his knife. As he is descending with the knife, Abraham is in union with God. Abraham at this point represents divine will itself. Then an angel appears and says: "Stop that!"
Kierkegaard implies at the outset that if you saw someone behaving this way, you'd probably want to call the police.
You can make whatever sense you want of it: Keirkegaard referred to himself as a poet. I understand him to be pointing to something (that was very important to me at the time I read it): not using Abraham as an example of how people should behave in general.
Since Abraham is in union with God, the story shows God in conflict with himself. Some would see connections to the Hindu triple idea of: God the destroyer (the God of Noah), God the creator (the God of Adam), and God the preserver (the God of Isaac).
I personally believe the actual Bible story has its roots in Semitic sacrificial traditions that may have at one time involved the sacrifice of children. This story is saying: don't sacrifice children, sacrifice sheep instead. Historically, the Israelites were horrified at the possibility that other Semitic people might be sacrificing children. I understand that it is now in question whether the Phoenicians ever did that, or just had a reputation of doing it. The Carthaginians apparently did. But the associations go on: Jesus is called the Lamb of God... this is a reference to the idea that Jesus was the final sacrifice, and no more sacrifices were necessary... so an evolution out of literal sacrifice into abstraction.
Anyway.. Keirkegaard isn't speaking as a religion scholar or as an ethics expert when he uses the story to point to a profound conflict at the core of human understanding of the divine. He also refers to fear (to the point of awe) at entering further into conceptions of God through contemplation.
I think the bottom line is, read Fear and Trembling. If it means something to you, then you are one of Keirkegaard's "readers." He knew he wasn't talking to everybody... only to his spiritual kin.