Why Not Just "Believe"?

In John Piper's classic 1986 book, DESIRING GOD: MEDITATIONS OF A CHRISTIAN HEDONIST, he asks and answers the question, "If your aim is conversion, why don't you just use the straightforward, biblical command, 'Believe in the Lord Jesus and you will be saved'? Why bring in this new terminology of Christian Hedonism?" His response is worth quoting at length since what John was  trying to achieve (calling people to true, saving, joy-filled faith) needs to be carefully and intentionally pursued by Christians in every generation. Also, what he is trying to avoid (leading people to engage in spurious faith that inoculates them to their need for the gospel) also needs to be combated today.

My answer has two parts. First, we are surrounded by unconverted people who think they do believe in Jesus. Drunks on the street say they believe.... Elderly people who haven't sought worship or fellowship for forty years say they believe. All kinds of lukewarm, world-loving church attenders say they believe. The world abounds with millions of unconverted people who say they believe in Jesus. 

It does no good to tell these people to believe in the Lord Jesus. The phrase is empty. My responsibility as a preacher of the gospel and a teacher in the church is not to preserve and repeat cherished biblical sentences, but to pierce the heart with biblical truth.

This leads to the second part of my answer. There are other straightforward biblical commands besides 'Believe in the Lord Jesus, and you will be saved.' The reason for introducing the idea of Christian Hedonism is to force these commands to our attention. Could it be that today the most straightforward biblical command for conversion is not, 
"Believe in the Lord," but "Delight yourself in the LORD"? And might not many slumbering hearts be stabbed broad awake by the words, "Unless a man be born again, into a Christian Hedonist he cannot see the Kingdom of God"?

Lord, grant us grace not only to delight our self in the LORD, but also to be your instruments in bringing others to do the same!