WHAT IS GOING ON in Detroit right now is enough to send certified liberals straight to the atlas to find out where on earth Australia is. The Republicans have taken the Equal Rights Amendment out of their platform, put in a constitutional amendment banning abortions, and are busily resurrecting congressional committees to track down subversives.

They got one this week. Mary Crisp, the Republican National Committee cochairman who repeatedly has stuck to her guns and backed the ERA, officially was purged. She was made a nonperson in convention literature and in its platform proceedings. Of course, the Republican conservatives aren't as adroit at purging dissenters as say, the Stalinists in the Soviet Union or the ayatollah in Iran. They didn't cart Mary Crisp off into the night, never to be heard from again. Instead, they gave her one more opportunity to speak up in public and she let them have it right between the eyes.

She told the Republican National Committee that the party was "suffering from serious internal sickness." She warned that its rigid antiabortion stand and its abandonment of its 40-year support for the ERA could cost the party the White House in November. "Now we are reversing our position [on the ERA] and are about to bury the rights of over 100 million American women under a heap of platitudes," she told her shocked audience. "Even worse is the fact that our party is asking for a constitutional amendment to ban abortions."

Republican feminists never thought they had a chance of preventing a party plank that would call for a constitutional amendment to ban abortions. That fight was clearly lost in 1976 when support for the constitutional ban first appeared in the platform. But they did think they had a shot at persuading Ronald Reagan that, in the interest of party unity, he should agree to keep the ERA in the platform, tell his conservative backers he did not want an ERA fight, or at least come up with some compromise on the issue. The feminists wanted to find some way to vote for a Republican candidate who was adamantly opposed to ERA and adamantly for an amendment to ban abortions.

"Obviously he's going to control the convention," said a Republican feminist shortly after Reagan went over the top in the delegate count last May. "If he wants [the ERA] taken out, it will be taken out. Or he can quietly put out the word that he doesn't want it to become an issue, that he can keep it in the platform. That will be a signal that maybe he's a little more of a practical politician than a rigid ideologue."

There is some question whether Reagan or the conservative zealots are controlling the convention and whether he might be getting a dose of what single issue politics is all about. But there doesn't seem to be much question at all that Reagan saw no need to compromise or accommodate the moderates and feminists in the party. All they got from Reagan was a sentence added to the plank that said: "We acknowledge the legitimate efforts of those who support or oppose ratification of the Equal Rights Amendment." That replaced: "We reaffirm our party's historic commitment to the Equal Rights Amendment and equality for women."

The rest of the plank states: "We support equal rights and equal opportunities for women, without taking away traditional rights of women such as exemptions from the military draft. We support the enforcement of all equal opportunity laws and urge the elimination of discrimination against women. We oppose any move that would give the federal government more power over families."

The plank condemns the efforts of the Carter White House on behalf of the ERA and says, in effect, the federal government has to stop pressuring unratified states into ratifying.

Now you might get the idea from all of this that if the Republicans don't watch out, President Carter single-handedly is going to get ERA passed. This must seem terribly ironic to President Carter, who was informed he would not be endorsed for reelection by the National Organization for Women because he had not done enough for ERA, in particular, and for women, in general.

The White House has responded with a four-page briefing paper outlining all the meetings and strategy sessions that Carter, his family, and his advisers have had on the ratification drive and all their activities on behalf of extending the deadline for ratification. And while it all sounds good, there are three more states needed to ratify the amendment and not a single one has done so since President Carter took office.

Jimmy Carter, for all his efforts on behalf of ERA, hasn't made much difference. If anything, he has established that lukewarm or enthusiastic support from the White House is not particularly vital to the success of the ERA. So why the fuss? What really happens in Detroit?

The Republican Party got into its time machine and took a giant leap back into the 50s. The party left moderation and tolerance of dissent behind. The platform and the candidate and the party's officials have to be ideologically pure. People such as Mary Crisp, who have the courage of their convictions and the guts to take a stand, got their loyalty questioned.

As Ronald Reagan so nastily put it: "Mary Crisp should look to herself and find out how loyal she's been to the Republican Party for quite some time."

What happened in Detroit probably won't have any real impact on the future of the Equal Rights Amendment. But the Republican feminist who said the ERA issue would tell whether Reagan is a practical politician or a rigid ideologue is getting her answer.