Third, we understand that the fight for joy is first and always a fight to see. Seeing the glory of Jesus Christ in the gospel awakens joy. And joy in Christ magnifies his worth. That is why Satan aims chiefly at blinding us from seeing Christ for who he is. He hates to see Christ honored. And Christ is mightily honored when the sight of his glory gives rise to the kind of gladness that cuts the nerve of sin and causes radical sacrifice in the cause of the gospel.
– Piper, John; When I Don’t Desire God: How to Fight for Joy; copyright 2004; Crossway Books; Wheaton, Il.; p. 43