Man has recovered his nerve, 2000 years after he lost it. Emmanuel G. Mesthene, a Harvard export on technology, told the delegates to the World Conference on Church and Society in Geneva Wednesday.

"We are ready to probe whatever our imagination prompts us to," he said. "We are convinced a gain, for the first time since the Greeks, of the essential intelligibility of the universe: there is nothing in it that is in principle not knowable."

Speaking to the 410 laymen and theologians who had assembled to tell the World Council of Churches, the churches should stand on major issues, Mesthene--director of he Program on Technology and Society--said that "technology has come of age" as a social phenomenon as well as technical capability.

"We are beginning to use invention as a deliberate way to deal with the future," he explained.

The churches, Mesthene said, will have to accept the feeling of confidence man gets from his new-found mastery of nature. "To see a sense of failure as a condition of religious experience is a historical relic dating from a time when an indifferent nature and a hostile world so over-whelmed men that they gave up thought for consolation."

The churches new role, he observed, will be to show the goodness and wisdom of God to men.

There was some grumbling among the delegates from Africa. Asia and Latin America about the relevance of the whole discussion of social problems accompanying advanced technology. "That is like talking to me about the problems of over-eating when I haven't got any food," one African objected. The impact of technology may be dehumanizing, but I don't think that's anything as bed as poverty."

The objection was one sign of the extent to which the conference is likely to be dominated by a discussion of the relations between rich and poor nations, a topic formally on the agenda.

The two-week conference, now in its fourth day, is the first ecumenical meeting of this kind at which most of the participants are laymen. It is also the first such meeting at which there are more delegates from Asia, Africa and Latin America than from North American and Western Europe.

Nearly half of the participants are from underdeveloped countries.

This is the third international conference on so big a scale for discussing Christian positions on issues that are normally considered secular. The first was held in Stockholm in 1925, the second at Oxford, England, in 1937.

The World Council of Churches, the sponsoring group, is an association of more than 200 Protestant, Anglican, Orthodox and Old Catholic churches in 30 countries. The Council has the broad aim of Christian unity.