Like many other pastors, I’ve often tried to explain the true depth and breadth of biblical joy. I don’t think I’ve ever expressed it as well as Kevin Vanhoozer does here:

joy is the mood that best accords with being-in-Christ.  Joy is not a feeling, like happiness.  Pastor-theologians are not here to produce happy Christians, saints with smiley faces.  Happiness is too shallow a term and fickle an emotion.  Happiness is dependent on circumstances, and circumstances change.  Often happiness is either inappropriate or inauthentic in our in-between times, marked by finitude and suffering.  By way of contrast, resurrection joy is a mood, a way of being attuned to the world – when one knows that the world includes an empty tomb.  Happiness is a surface phenomenon, but for those who through faith enjoy being-in-Christ, joy resides in the depths of their being.  Joy is never inappropriate, even in the depths of suffering (e.g., funerals), because the resurrection reminds us that death, foe though it be, has been defeated, along with its cohorts meaninglessness and hopelessness.  The psalmist declares, “I will sing praises to my God while have being” (Ps. 146:2 RSV).  The Great Reversal has taken place.

The Pastor as Public Theologian, page 107