Katharine Welby, daughter of the Archbishop of Canterbury, has been speaking about her "battle with depression". Met by tremendous sympathy, she has responded by launching the public presentation of the "Happiness Course". This is an Alpha-course lite - positive thinking and no Gospel. One might ask why the daughter of the Archbishop thinks this is a wise move, given her profession of faith as expressed on her own site. Where is the common ground?

The common ground is in the language of humanism as determined by one word: depression. Miss Welby thinks of depression as a disease, an affliction, a trial. She is bold in doing so, in the face of a Church that likes to pretend that as role models to the world, Christians must be perfect. And that is why she will be welcome to everyone - Christians will have sympathy and humanists will rejoice to see a Christian who admits that she still has problems.

I faced the issue of unhappiness in the soul of the Christian whilst writing The Life of William Cowper. Cowper is the caricature of depression to many Christians. They use him as an excuse, not knowing the man or the reality of his own sorrow. That Cowper had reasons for times of sadness and that his "depression periods" followed crises in his life, takes this so-called disease and turns it into nothing but ordinary reactions to sorrow. These gave rise to some dark thoughts - not doubting God, but doubting his own salvation from time to time. But this is a million miles away from "depression", in the clinical, psychiatric sense. This is a Christian man, facing problems and sometimes buckling under the pressure.

By her own admission, Miss Welby has had a great family, great boyfriend, great job, great church. She seems to be "suffering" from having everything, which is supposed to make someone happy and finding that it isn't enough.

I am not unsympathetic with her plight, but sympathy must be tempered because her influence to do harm has increased with her father's public role as Archbishop of Canterbury. And if this new venture is "something to do" and an unconscious attempt on her part to appease her conscience and normalise her problems, then it will end badly.

There are real things about which people ought to be depressed. The first of these is sin. Sin makes us guilty before God. If we don't repent then we are going to Hell. So all humanists should be suffering from depression and any effort to cheer them up without the Gospel message (the true good news) is pernicious.

There are real problems for Christians after they are converted. The present state of culture, conquered by humanism through the weakness of the Church, is reason for Christians to be unhappy! In addition, Christians have problems, cause problems and are problems. There is no immunity from unhappiness. But there is joy.

Joy is not a feeling. It is expressive of the peace in God the Christian knows, a peace which does not make Christians grin in storms and feel no pain, but allows faith in God to surmount these fears. Miss Welby's fears are the common complaint of our present society: why am I here? Mixed with Christian knowledge, her problem can only be exacerbated. She needs a mission. She needs a distinctive purpose and goal.

We are so much "wiser" than our forefathers. It is not enough to say "Man's chief end is to glorify God an enjoy him forever". Christians want to be seen to be active. They want success on the world's terms. They want to be happy.

The Christian's duty is to seek God's glory so fervently that our personal happiness can be sacrificed from time to time. But that doesn't fit the agenda:

 In my hopelessness I just need to acknowledge that God is bigger than my illness and he will come through – eventually.