“Nothing is so contrary to godliness as levity,” contended John Fletcher, for “Jesting and raillery [teasing], lightness of behavior, useless occupations, joy without trembling and awe of God, an affection of vivacity and sprightliness, are all contrary to the Spirit of God.”  He puts forward the sobering question, “Are we not walking in the presence of God—on the verge of the grave—and in the sight of eternity?” and concludes, in a word, that “All who walk with God are serious.” Seriousness of mind is in view in 1 Peter 5:8: “Be sober-minded; be watchful. Your adversary the devil prowls around like a roaring lion, seeking someone to devour.” Christians have a serious adversary, so Christians need to be serious.
But how does this consist with the Church being characterized as a happy people? Those who enjoy God’s favor are implored, “Serve the Lord with gladness! Come into his presence with singing!” (Ps. 100:2). If Christianity is holiness and happiness, as we contend that it is, how are we to be both sober and joyful? This question may be easily answered by asking another: What do we mean by happiness?
If happiness is the kind of giddy, stupid feeling that is alluded to in a thousand trite remarks, then it is indeed incompatible with godly sobriety. An old song by Al Stillman and Dick Manning offers a revealing quip:
Where it goes
No one knows!
What’s in store
Who can guess?
It could be happiness!
If happiness is the kind of thing that comes and goes, then one may as well ride the world’s happy wave, surfing from one high to another, and sit out sad moments, hoping that the happy tide will come rolling back in. Those who are constantly fooling around, occupying themselves with “innocent” pleasures, or browsing for a snippet to spark their joy, may spend much time laughing and smiling, but they are fundamentally unhappy people. Biblical happiness is qualitatively different than the kind of joy that is afforded by worldly amusements. True happiness—the pleasant, peaceful assurance of God’s favor and fellowship—is deep as God is deep.
Fletcher knew that he could be easily misunderstood, and anticipated the question, “Are we to be dull and melancholy?” He answered brilliantly: “Seriousness and solid happiness are inseparable.” Christian happiness is solid happiness. It is not curt or unsmiling, but it is certainly not light or flighty. A Christian’s solid happiness sometimes overflows in jubilant songs and dances, but these exultations are as different from worldly ecstasy as a rushing river is incomparable to a spritzing spring. Worldly happiness spritzes, but it is always dry when it really counts. Christian joy never runs dry, but springs up into eternal life.
Christian happiness is solid because it is rooted in solid things, and solid things must be taken seriously. In the sober study and contemplation of eternal matters, we find our delight, and say with the Psalmist, “Your testimonies are my heritage forever, for they are the joy of my heart” (Ps. 119:111). Worldly joy is fixated on hevel, smoke, vanity of vanities, and inevitably wisps away.
Christian happiness is solid because it is rooted in solid things, and solid things must be taken seriously.
If you are always looking for the fun in life—the joke, leisure, or entertainment—you probably already know, in the secret place of your soul, that true happiness is eluding your grasp. The paradox of Christian happiness is that it flows from a period of mourning over sin then settles into a steady stream through a serious, lifelong battle against everything that is less than excellent. Christian joy is always mingled with reverence and only comes to those who “Serve the LORD with fear, and rejoice with trembling” (Ps. 2:11). If you want to be happy—really happy—you must quit playing games and find a place to pray. Or, as James says, “Let your laughter be turned to mourning and your joy to gloom. Humble yourselves before the Lord, and he will exalt you” (Ja. 3:10). Seriousness is not opposed to joy. It is the inescapable path to and abiding attitude of solid happiness.
 Fletcher, John. Works of Fletcher: Volume IV, Miscellaneous (Salem, OH: Schmul Publishers, 1974), 250.