Now I know that you love me

I had one of those "ahhh" moments over this little section from Counterfeit Gods, by Tim Keller. He has been discussing God's requirement of Abraham in testing whether or not he would sacrifice Isaac ("your son, your only son, Isaac, whom you love" - Genesis 22:2). I always read that story and feel the great agony that must have been for Abraham (even though I don't have kids!) and finish up in awe of what he did. Then mostly from there I go to something like 'God provided the substitute lamb for the sacrifice for Abraham, and then later he sent Jesus to be the ultimate substitute sacrifice ...'. This, however, is slightly different:

We have to know, to be assured, that God so loves, cherishes, and delights in us that we can rest our hearts in him for our significance and security and handle anything that happens in life.

But how?

God saw Abraham's sacrifice and said, "Now I know that you love me, because you did not withhold your only son from me." But how much more can we look at his sacrifice on the Cross, and say to God, "Now, we know that you love us. For you did not withhold your son, your only son, whom you love, from us." When the magnitude of what he did dawns on us, it makes it possible finally to rest our hearts in him rather than in anything else.