Interior Secretary James G. Watt and his wife, Leilani, are leaders in the Reagan administration's support of the Holocaust memorial museum. As "persecuted evangelical Christians," Watt said, he and his wife are sensitive to the possibility that "a Holocaust can happen again."

"Unfortunately in our tenure here we have experienced the hatred that has been poured out, and can see that there's the threat of the seeds of the Holocaust-type mentality here in America," Watt said in a recent interview in his office. His wife was there at his request.

"We've had the religious persecution in the media and by special interest groups," Watt said. He said this "makes us all the more aware of fighting continually for political liberty and spiritual freedom."

A spokesman in Watt's office said Watt is an evangelical Christian who frequently attends Assemblies of God churches.

Leilani Watt, who was the host at a White House reception and viewing March 14 of a wrenching Holocaust documentary, "To Bear Witness," for several hundred influential American Christians and Jews, said the film is so moving that it demands "a response in today's world." Asked what response, she looked to her husband, who said emphatically, "Go ahead, tell him what we feel!"

Carefully emphasizing her words, she said: "This film demands a response, and my response is: What is the difference between seeing those bodies in the Nazi death camps stacked up to be burned, and fetuses stacked in plastic bags ready to be thrown out? So my personal response was, how can you be for abortion? It's the annihilation of a whole race of people.

"My second response was, how can we not have a strong defense in America? . . . Germany had asked to be at peace with its neighbors, and then . . . you see them toppling one nation after another with no strong defenses . . . Germany could just walk in."

Watt said his reaction was "the political one . . . that we must not allow the centralization of power that would destroy the dignity of an individual . . . We saw what Hitler did with his centralized dictatorial powers . . . And it can happen again. That's the message that Congress wanted to be taught" in approving the Holocaust museum.

"We're not suggesting that any other person has to have this response," said his wife.

". . . And I think this is the beauty of it," said Watt. "I mentioned this response on abortion to one of the artists who worked on making the film . . . and she said, 'There's no way anybody can think of abortion when you see this film.' . . . So I said, 'That's great . . . This film doesn't dictate.' "

Later in the interview, Leilani Watt returned to the abortion theme after her husband, his voice intense with emotion, said, "The surprise of the Holocaust era was not that so much evil could come out of one man, Hitler, but that so many people could fail to do good . . . Those people shown in the film , those good people lived in a town nearby while millions were hauled and marched to their death, and they smelled the stench of burning flesh in the town nearby and did nothing."

"Actually," said his wife, "it was that statement, 'living in the town nearby,' that so captured me concerning abortion . . . I had lived in the town nearby, what had I really done to stop abortion in America? . . . Personally I'm against it, but what had I done vocally, how had I spoken up? I saw it, yes, but what did I really do?"