For the religious leaders who have fought against giving U.S. aid to antigovernment forces in Nicaragua, the House of Representatives' 222-to-210 vote Thursday against such a measure was "the easy one," said one of the veterans of that fight.

But Edward Snyder, head of the Friends Committee on National Legislation, said yesterday there will be "no letdown" in efforts by the church lobby get the Senate to defeat, in a vote expected next week, its variation of the administration-backed measure to send $100 million to the contra forces.

There have been few issues since the Vietnam war that have so mobilized mainline religious forces in this country as the question of U.S. aid to the forces seeking to overthrow the Nicaraguan government.

Rep. Michael Barnes (D-Md.), who helped mobilize the defeat of the contra aid package, praised religious forces for their role in the battle. "They have been very vocal, very effective," said Bill Bronroott, Barnes press aide. "We think they have been very influential during the debate."

With the national representative assemblies of more than a dozen Christian and Jewish denominations formally on record as opposing, in principle, U.S. military intervention in Nicaragua, church lobbyists had a solid base for their opposition to the aid package.

Religious groups that have formally voted opposition to rebel forces in Nicaragua include the United Methodist, Presbyterian, Episcopal, American Lutheran, Mennonite and American Baptist churches; the United Church of Christ; the Christian Churches; the Lutheran Church in America; the Union of American Hebrew Congregations, the Unitarian Universalist Association, the National Board of Jesuit Social Ministries and the United States Conference of Catholic Bishops.

As House debate on the aid bill heated up in recent weeks, many of these groups made certain that members of Congress were aware of the positions taken on the matter by millions of their constituents in the religious community.

White House tactics of clothing the political conflict in religious garb appears to have backfired. President Reagan's repeated appeals for support of the contra aid package, with his graphic claims of Sandinista assaults on religion in Nicaragua, drew angry retorts from some religious leaders.

In an uncharacteristically blunt letter to the president, the presiding bishop of the Episcopal Church wrote, "I do not think I am alone in finding it less than helpful for our national leaders to coin or corrupt the language of our democracy in support of questionable foreign military forces.

"Identifying the contras as 'freedom fighters' obscures the issues in an attempt to attach the contras to the historic memory of the United States. To disregard the reports of reputable international human rights agencies or undermine their credibility and legitimacy . . . does not seem to serve the interests of our national decision-making process . . . nor enhance the vital work of independent, international human rights agencies and advocates," the Rt. Rev. Edmund L. Browning wrote.

The Rev. Leland Wilson, the Central America specialist for IMPACT, a Washington-based coalition of religious activists, told a breakfast briefing on Tuesday that the Reagan administration's position was "a facade of falsehoods and lies.

"The administration says it has supported the Contadora process" calling for negotiation. "That's a lie," said Wilson.

"The administration says the church is being destroyed in Nicaragua," he continued. "That's a lie. The administration says Nicaragua is a threat to its neighbors and the security of the region. That's a lie. The administration claims the support of our Latin American neighbors" for the U.S buttressing of the contras. "That's a lie."

While much of the religious community's opposition focused on the $70 million for military aid in the administration package, some, like the heads of eight international relief organizations, also challenged the $30 million for "so-called humanitarian assistance."

Characterizing such aid as humanitarian "distorts the concept of humanitarian aid as understood internationally and in the United States," the agency heads said in a statement sent each member of Congress.

"It does not meet the customary tests: that humanitarian aid be made available solely on the basis of human need, not for political purposes; that it be offered impartially to all sides in a conflict, and that it go solely to civilians and noncombatants.

"Mislabeling the $30 million imperils the integrity of bona fide humanitarian aid" and "risks the future of people whose life depends on it," they said. The statement was signed by heads of Lutheran, Roman Catholic, Mennonite, Quaker and Unitarian Universalist agencies as well as Church World Service, Heifer Project International, and Oxfam America.

The U.S. Catholic bishops, while acknowledging "very critical" human rights violations in Nicaragua, nevertheless opposed the contra aid package, calling instead for the negotiations supported by other Latin American nations.