Members of the Moral Majority may have taken up residence in some offices of the Reagan administration. But when the computers at NASA's Goddard Space Flight Center began spewing paper with religious ads for related groups on the back, some employes wondered if Jerry Falwell's crew had taken over.

The ads included a "special pre-publication offer of the King James Bible" from Falwell and the opportunity to buy a family communion kit from Jim Bakker's PTL Club, in Charlotte, N.C. The PTL stands for Praise the Lord.

The answer, though, involved another government cost-saving effort.

"We use enormous quantities of computer paper, and you hate to pass up a cost savings these days," said Robert Kraemer, who oversees Goddard's computer operations. A box of 2,500 sheets of the 11 x 15 paper costs $18.50, but only about $14 if it has been used, he said.

"It raises an interesting question of policy," he said. "Do we need to specify what can be on the back side of the paper we buy?"

Bob Daniels, director of marketing for the PTL Club, said 95 percent of its mailings are done in-house, but some were done by Communications Corp. of America Inc., of Culpeper, Va., apparently the source of the used paper that ended up at NASA.

An astonished Bob Hardy of CCA said his firm had turned the misprinted computerized mailings over to "salvage operations" as trash, never expecting them to be resold to NASA.

PTL's Daniels said, "We're not happy with that situation, if some of the names on our mailing list ended up at a federal agency. We do use caution to maintain the confidentiality of the lists."

Chuck Mason, director of data processing for NASA, said, "I'm a little stunned that that paper would turn up here." He said all NASA operations have been told to buy "white-on-white with no printing anywhere."

"We only use this internally, not for material that would be kept permanently or for information that would go out of the center," Kraemer said.