Why did Jesus die for us?

Why did Jesus die for us? What was Jesus getting out of it? Remember, he already had a community of joy, glory, and love. He didn't need us. So what benefit did he derive from this? Not a thing. And that means that when he came into the world and died on the cross to deal with our sins, he was circling and serving us. "I have given them the glory that you gave me" (John 17). He began to do with us what he had been doing with the Father and the Spirit from all eternity. He centers upon us, loving us without benefit to himself. (emphasis mine)
Tim Keller in The Reason for God

When I read this it hit home. In my limited understanding, I've always pictured God getting some benefit out of us. For instance, the Westminster catechism describes the main purpose for human existence is to glorify God. In my mind that means that God's benefit is being glorified by us. Or the fact that the biblical story is about God redeeming a people for himself. In my mind that means that God's benefit is getting a people for his own possession (this is, in part, very biblical by the way).

The problem with these statements is that I have been finding an intrinsic value in myself and other Christians. How is this a problem? In a subtle way I've been believing that God's love is, in part, a self serving love. As if He's getting something out of the deal. Oh, the arrogance of that statement!

The realization that Jesus already had the perfect community of joy, glory, and love means that he needed nothing. This also means that His sacrifice was one of pure love and in no way self serving.