From this passage, a couple things can be observed. First, it is apparent that the Congregationalist Calvinists of Edwards’s day were already experiencing a bit of criticism because they did not laugh enough and (it seems) took life too seriously. Second, you can see in Edwards’s response to this criticism, that he believed it to be a gross caricature. As far as Edwards was concerned, this was the complaint of those who did not know the true joy and happiness that came with being a Christian. True Christian joy goes deeper than the momentary laugh.
This excerpt comes from the sermon, “True Love to God”:
One great reason why religion is judges to be melancholy is because it has no tendency to raise laughter, but rather to remove it; but that is no argument against the pleasantness of religion, for the pleasure that raises laughter is never great, is only flashy and external. This everyone knows by experience. Even the greater sort of worldly pleasures themselves don’t raise laughter. The pleasures of religion raise one clear above laughter and rather tend to make the face shine than screw it into a grimace. Indeed, the pleasures of religion when in their height do cause there to be a sweet, inexpressibly joyful smile in the countenance, and the reason why religion is not always attended with such a smile is because we have so many sins to lament and be sorry for, but repentance itself is attended with pleasure as we have shown.
Jonathan Edwards, Sermons and Discourses, 1720-1723, vol. 10 of The Works of Jonathan Edwards, ed. Wilson H. Kimnach (New Haven, Conn.: Yale University Press, 1992), 642.