Missing the Point in Genesis 22

This article in the Huffington Post on Genesis 22 misses the point concerning the book of Genesis in general and the significance of the binding of Isaac episode in particular. In the article, rabbi Sid Schwarz suggests that the main point was really about Abraham's repentance ("return") concerning his mistreatment of Ishmael! As I read Genesis, one of the main themes of the book is the fulfillment of God's promises through an elect line, a line that includes Isaac but not Ishmael. Whether Abraham should have treated Ishmael differently is debatable, but I seriously doubt that Abraham's treatment of Ishmael was what God was trying to teach him on Mount Moriah.