Joy and the Gospel: a responsibility

In his book, Spiritual Depression, Martyn Lloyd-Jones gives a compassionate and truth-oriented treatment of the topic. In the quote below, he address the fact that a lack of joy undermines the credibility of the gospel:

But there is another and more important reason, which is that we must face this problem [of spiritual depression] for the sake of the Kingdom of God and for the glory of God. In a sense a depressed Christian is… a very poor recommendation for the gospel. We are living in a pragmatic age. People today are not primarily interested in Truth but they are interested in results. The one question they ask is: Does it work? Nothing is more important, therefore, than that we should be delivered from a condition which gives other people, looking at us, the impression that to be a Christian means to be unhappy, to be sad, to be morbid, and that the Christian is one who 'scorns delights and lives laborious days'. There are many indeed who give this as a reason for not being Christian, and for giving up all interest they may ever have had in the Christian faith. They say: Look at Christian people, look at the impression they give! And they are very fond of contrasting us with people out in the world, people who seem to be so thrilled by the things they believe in, whatever they may be. They shout at their football matches, they talk about the films they have seen, they are full of excitement and want everybody to know it; but Christian people too often seem to be perpetually in the doldrums and too often give this appearance of unhappiness and of lack of freedom and of absence of joy. There is no question at all but that this is the main reason why large numbers of people have ceased to be interested in Christianity. And, let us be quite frank and admit it, there is a sense in which there is some justification for their attitude, and we have to confess that their criticism is a fair one. It behooves us, therefore, not only for our own sakes, but also for the sake of the Kingdom of God and the glory of the Christ in Whom we believe, to represent Him and His cause, His message and His power in such a way that men and women, far from being antagonized, will be drawn and attracted as they observe us, whatever our circumstances or condition. We must so live that they will be compelled to say: Would to God I could be like that, would to God I could live in this world and go through this world as that person does. (Martyn Lloyd-Jones, Spiritual Depression)