The governing board of the National Council of Churches wound up its three-day meeting here today with a flurry of actions and resolutions sharply critical of U.S. policy in Central America.

After spending most of two days attempting to make the council's internal structure more responsive to the 31 member denominations that pay the bills, board members spent their final day on social justice issues.

The policy makers for the nation's largest organization of Protestant and Orthodox Christians gave tacit support to a burgeoning grass-roots movement enlisting sympathizers to use nonviolent resistance against any U.S. military intervention in Central America.

The board stopped short of formally endorsing the "Pledge of Resistance," which reportedly has 60,000 signers committed to physical resistance to any U.S. military action in Nicaragua.

But the resolution on the Pledge of Resistance movement, overwhelmingly adopted here, urged member churches and individual Christians "carefully to consider their corporate and personal responsibilities as Christians and citizens at this time for U.S. policy towards Central America."

It urged leaders of member churches "to provide churches and individual Christians with guidance" as they contemplate "engaging in nonviolent acts of resistance." Those who sign the pledge, the resolution said, "have placed themselves within an important stream of U.S. history . . . a long tradition of nonviolent resistance to injustice," comparable to abolitionists suffragettes and civil rights leaders.

During today's debate, several board members indicated they had signed the Pledge of Resistance.

Jane Cary Peck of Williamstown, Mass., noting that "the president has not heeded our calls" for peaceful negotiation with Nicaragua, said she had signed the civil disobedience pledge "as the only recourse."

Last week, the NCC's president, Bishop Philip R. Cousin, and General Secretary Arie R. Brouwer sent a letter to President Reagan sharply criticizing the trade embargo against Nicaragua. They also scored the "administration's continued affirmations of intent to bring down the government of Nicaragua by whatever means available, including armed force."

Another resolution adopted today encouraged member churches "to give serious consideration to the Sanctuary Movement as an expression and embodiment of the Christian's duty to the suffering stranger."

But the resolution also warned that in doing so, churches face "risk of criminal prosecution, expenses of legal defense and possible fine, imprisonment or restrictive conditions of probation as well as criminal record."

The NCC reiterated its appeal to U.S. authorities to grant "extended voluntary departure to groups needing such protection," specifically Salvadoran and Guatemalan refugees.

The resolution also sharply condemned "the infiltration of churches by government agents to apprehend workers in the Sanctuary movement," a practice that resulted in the indictment of a number of church leaders earlier this year.

A resolution on South Africa charged that the Reagan administration policy of "constructive engagement" has "proven ineffective."

It urged instead the comprehensive, mandatory and multilateral sanctions against South Africa adopted by the General Assembly of the United Nations.

Board members gave a prolonged standing ovation to Chicago's Roman Catholic Cardinal Joseph L. Bernard, who stopped by to bring greetings and urged collaboration in "providing a voice for the poor and aid to the needy," in efforts for peace and disaster relief work.

Mayor Harold Washington also drew cheers in a cameo appearance during Chicago Churches' night. He told church leaders that he would not have been elected without the support of Chicago's churches.

Board members initiated moves to establish a special NCC department dealing with evangelism, as proposed by the new general secretary, Brower.

A resolution encouraging consultations with worldwide church groups as well as government to explore the reunification of Korea was approved.

Also adopted was a cautious, apolitical resolution expressing "concern for the hostages held in Beirut." It called for prayers for the hostages and their families and urged church members to "give more attention to understanding the suffering of the people of Lebanon, all of whom are victims of the ongoing conflict.