WHO have we been applauding in Desmond Tutu these past months? Except among close watchers of the South African scene, not much was known about the career and convictions of the former bishop of Lesotho and currrent general secretary of the South African Council of Churches. A few years ago, the congressional Black Caucus asked Tutu in for a lecture. The turnout was slight. For many, he was only another passing-through pleader asking Americans to pay attention.

Now that Tutu has won the Nobel Peace Prize, it is different. But he is not. Hope and Suffering, a collection of sermons, lectures and letters from the past decade, shows the stairs on which he was steadily climbing to world acclaim. Whether or not he had won a Nobel, Tutu, by the evidence in this small but stunning volume, would still have been a force that no regime could stop or silence. Still, he trips and nearly falls a few times on those stairs.

On the two recent occasions I heard Tutu preach -- at the Washington Cathedral with informal exchanges afterward -- I had the impression that his new role as South African prophet is one he would personally prefer to be without. He seemed to be more the parish priest than the public activist. Prayer, liturgy, theology and the sacraments are where his heart is. Racial justice and the politics of freedom are genuine commitments but not the essential vocation.

My hunch was confirmed. Tutu writes that "for me the most important -- the most cardinal -- fact about our life is the spiritual: that encounter with God in prayer, in worship, in meditation." Of his opposition to the South African government -- which includes opposition to the Reagan administration -- Tutu writes that "I do not do it because I like doing it. I do it because I am under what I believe to be the influence of God's hand. I cannot help it: when I see injustice I cannot keep quiet. I will not keep quiet, for, as Jeremiah says, when I try to keep quiet, God's word burns like a fire in my breast. But what is it that they can ultimately do? The most awful thing that they can do is to kill me, and death is not the worst thing that could happen to a Christian."

He doesn't say what it is, except by implication: the unwillingness to risk for the faith. Tutu the risk-taker is more to be honored than Tutu the political theorist. He is dead wrong when discussing racial alliances. "We have been deeply hurt," he writes. "We have seen that when it comes to the matter of Black freedom then we Blacks are really expendable in the view of the mighty U.S. It was a case of blood being thicker than water. You can't really trust Whites. When it comes to the crunch, whatever the morality involved, Whites will stick by their fellow Whites." That isn't fiery rhetoric, it's flammatory falsity. What, for example, of the numberless white missionaries in Africa in the past decade who stayed with the blacks they were serving only to be martyred by marauding black soldiers?

In an essay on the population removals of South Africa, Tutu forcefully describes the suffering endured by blacks. "People are starving in most of these resettlement camps. I know, for I have seen it. They are starving not because of an accident or a misfortune. No, they are starving because of a deliberate Government policy made in the name of White Christian civilization." What's needed right there is a balancing sentence or two, a few words on the starvation caused by the ineptitude and violence-based policies of some of Africa's black governments.

The most serious oversight in Hope and Suffering is the absence of an essay on nonviolence. Martin Luther King's "Letter From a Birmingham Jail" and his essay on "Forgiveness" are testaments to the effectiveness of nonviolence, but Tutu offers only a few sentences on what should be the most crucial part of his witness. "Our people are rapidly despairing of a peaceful resolution in South Africa. Those of us who still speak 'peace' and 'reconciliation' belong to a rapidly shrinking minority. And if they decide to fight, they know they can't go to the West for support. So we are paradoxically being driven into the arms of the Soviets to get our arms, by the very country that is concerned about Soviet expansionism."

There is probably little hope for it now, but Desmond Tutu ought to take the time -- perhaps an hour a day in his study -- and write a book that goes into his own deepnesses. What's offered here is useful, but it is too much a mixture of strengths and weaknesses. It is not held together by a prose style of any kind. Only now and again, does a line leap from the page, and the leaps aren't that high.

Perhaps it is too much to ask that men of God and peace be also men of literature. I recall an answer Tutu gave to a reporter's poignant question at the Washington Cathedral: How do you manage to be so cheerful a person amid such suffering in South Africa? He explained that the tears of joy and the tears of pain come from the same place -- the human heart.

That, too, might be an answer for Tutu to think about when he wonders whether it is time to write a truly memorable from-the-heart book, not merely, as this is, a topical one from the head.