Christian decisions on life and death issues must be based on all the sources of faith -- including the scriptures, dogma, Christian history and tradition -- instead of proof-texts or specific references from the Bible, a leading Roman Catholic theologian said here.

Drawing on those resources, which he termed "the Christian story," the Rev. Richard A. McCormick of the Kennedy Institute of Ethics at Georgetown University, in a lecture here this week, projected a series of Christian theses on bioethical issues:

* Human life is "a basic good" but not an absolute good.

* The centrality of Christians' celebration of Jesus' birth is at the root of Christian opposition to abortion, although that position "does not settle the moral rightfulness or wrongfulness of any particular abortion." Neither does it address civic laws relating to abortion in a pluralistic society.

* In cases of grave illness or injury, loss of potential to relate to other human beings is a reasonable ground for refusing or discontinuing the use of extraordinary measures to prolong life. So is "profound and intractable pain."

McCormick's public wrestling with some of today's most difficult bioethical issues was the first of five lectures on ethics sponsored by the Kennedy Institute in honor of its first director, the late Andre E. Hellegers.

The institute was founded 10 years ago to encourage creative thinking on the relationship of religion to ethical problems and is considered a major resource in the field nationwide.

McCormick, who served on the now defunct Ethics Advisory Panel of the Department of Health, Education and Welfare during the Carter administration, acknowledged to the largely Catholic audience that "I write and think as a Catholic moral theologian" with his faith influencing his "perspectives, analyses, judgments." At the same time, he suggested, his approach grows out of the total human experience and is not an "eccentric refraction" of a particular faith.

He said one of the difficulties posed by "western secularized society" is that it "sees its task as protecting the individual's autonomy to do his/her own thing" and considers it the state's function "to guarantee and protect the right of noninterference."

In discussing his thesis that "life is a basic good but not an absolute one," McCormick pointed out that "there are higher goods for which life can be sacrificed" such as the glory of God, the salvation of souls, the service of others.

Taking issue with the tendency of modern medical technology to maintain life at all costs without regard to the quality of that life, he said, "An obligation to use all means to preserve life would be a devaluation of human life, since it would remove life from the religious context . . . that is the source of its ultimate value."

McCormick praised the living will composed by Sissela Bok. That document, after a strong affirmation of life, states in part: "If my death is near and cannot be avoided, and if I have lost the ability to interact with others and have no reasonable chance of regaining this ability, or if my suffering is intense and irreversible, I do not want to have my life prolonged."

Bok, said McCormick, has "identified the two conditions beyond mere circulation and ventilation that ought to be present before life makes life-sustaining claims upon us: some minimal potential for interrelating, and absence of profound and intractable pain."

On abortion, McCormick quoted two Protestant theologians, Paul Ramsey and Albert Outler, who derived their opposition from the long Christian tradition for the sacredness of human life and particularly, according to Ramsey, "the power of the nativity stories and their place in ritual and celebration and song."

McCormick added, "I judge that a simple pro-choice moral position -- I did not say legal position on abortion -- is in conflict with the biblical story." In answer to a question, McCormick said that the tendency "to conceive moral problems in legal terms is counterproductive." Christians who share his view that abortion is contrary to the Christian tradition, he said, need to do "a good deal more preparation, witnessing and persuasion . . . I feel a Christian has a duty to persuade in the public forum."

McCormick summed up his convictions about the relevance of Catholic insights into moral and ethical issues confronting society by quoting the United Church of Christ theologian, Roger L. Shinn of Union Theological Seminary: "They Christians do not expect the Christian faith and insight to be confirmed by unanimous agreement of all people, even all decent and idealistic people. But they do expect the fundamental Christian motifs to have some persuasiveness in general experience."