As a father of 3 awesome kids it is easy to find delight in them. They bring me so much joy as they walk with the Lord and lead others to a closer walk with Him. I can say, in a small measure, that I understand some of what The Father says when He says "The is my Son in whom I am well pleased". I am certainly well pleased with all of my kids.
The difficultly with me being pleased with my kids is that they are often like me. Our kids always get our traits, especially the ones we would rather them not get. The Father has no sinful traits to look past to see the glory of His Son. The Son is the pure radiance of The Father, and so He can be well pleased with The Son because there is no imperfections to overlook.
So then, if The Father is perfectly pleased with the Perfect Son, then it should go without saying that we can only stand in awe and wonder that The Father would lavish His love on us, that while we were yet sinner He would send His only Son to take our place on the cross and direct all of His wrath onto The same Son- whom He loves so very much. We who were dead in our sin, having no righteousness of our own, yet He loved us enough to make this great exchange; the righteous for the unrighteous.
The Son, likewise, was willing to be The Sacrifice for us. Think about that in a new, fresh way today. All three persons of the Trinity knew exactly what was going to happen and yet this was the plan to win sinful man back. How can this really be a good trade for God? How can allowing His beloved Son be tortured and killed be a trade worth making to win you and me? And after thinking about how "unbalanced" a trade that is, then think on the fact that God does exactly as He pleases and so He was pleased to make this trade.
When I see my kids playing sports, it reminds me of days gone by that will never come again for me. I like to see them excelling. It brings me delight, in sort of a strange way, that Grant beats me in golf and that there is no way I can compete with Garrett on the ball court. I am well pleased with their ability. But this is a small and temporary happiness compared to how well pleased I am when I see them reflect Christ in the way they treat others in those same competitions. When Kimmy goes to state in golf and gets the sportsmanship award, because even though she played really poorly the last day, she still reflected the Image of Christ to all those around her, and that is worth being well pleased.
"God is most glorified in us when we are most satisfied in Him". J. Piper. God is most pleased to call us His children when we are reflecting His Image. He doesn't cast us off when we are not reflecting, but He is most delighted in us when we are being conformed to the likeness of The Son. As a parent, I can take no credit for my kids Christ-likeness, as that only comes from His work in their lives. BUT, it is a joy to see them reflecting more of His image and that is the thing that makes me, and The Father, most pleased.
Delight yourself in the Lord and He will give you the desires of your heart. Ps. 37:4.