A WOMAN CALLED the other day and stated her credentials.She is a feminist. She has headed up this organization and that organization. She has been to all the required conventions and she subscribes to all the proper magazines and she has read all the required books. Her standing in the ranks of feminists is secure, yet she opposes abortion. This, she argued, does not strip her of her standing as a feminist.

But some people, she said, think it does. She and others like her are constantly being lumped in with women and men who are not feminist, who not only oppose abortion but also the Equal Rights Amendment and conscription for women and birth control and maybe, just for good measure, the 20th century. fShe resented this.

The woman went on. She is a liberal. She was raised in a liberal home and liberal causes are her causes. She has marched. She has protested. She has sat in and sat down and opened her purse for civil rights and civil liberties. She was a union maid from way back, but just because she is opposed to abortion she is being called a conservative -- a virtual reactionary. She was more than angry. She was upset.

She has a right to be. For too long now, abortion has been the sine qua non of a whole lot of movements. To many, it seems impossible that someone could be both a feminist and opposed to obortion. On the other hand, to many conservatives, it is just the other way around. The furor over Sandra O'Connor, President Reagan's Supreme Court nominee, is almost entirely over abortion, which is only, after all, one issue -- and maybe an issue that has already been settled. No matter. To some people, there is no way to be a conservative as long as you are soft on abortion.

It is the same with feminists. There is a certain validity to the view that abortion is sometimes opposed for what could be called anti-feminist reasons. Some people clearly think of pregnancy as punishment for sex, especially sex outside of marriage. In this view, anything that would eliminate pregnancy as an inhibiting factor -- abortion, birth control, sex education -- is to be opposed.

Similarly, there are some men who consider abortion threatening. They think it means a loss of the traditional control men have had over women. This may be the emotional force behind attempts to forbid abortions that are not approved by fathers or husbands. And this also may be why some women revert time and time again to that cliche about control over their own bodies, but it also has to do with someone else's body -- or the potential of one.

Still, there are people who want no control over women, who are not threatened by female sexuality, but who are nevertheless morally and ethically opposed to abortion. And to say, fine, hold that position, but don't try to impose it on others, begs the question. If I considered abortion to be murder, I would try through the political process to ban it. This is how I feel about capital punishment, and no one is going to tell me that I shouldn't use the political process to try to abolish it.

Politics is the proper forum for the abortion controversey. But abortion is not the one and only political issue -- not the one issue that defines who you are politically. The insistence that it be weakens not only the conservative movement but feminism as well. It is reminiscent of attempts throughout history to impose a doctrinal purity on large ideological or religious movements. People have always been told that they could not be what they wanted to be -- Christians or Jews or even Whigs -- if they did not believe such and such. When the communists attempted to do this, all they really succeeded in doing was contributing the term "party line" to the language.

Well, feminists, especially the more doctrinaire ones, are developing their own party line. They are attempting to define a movement very narrowly: You can't be against abortion. You can't be blase about pornography. You have to be blind to the real differences between men and women. You have to be this and you have to be that, but the fact of the matter is that all you need to be a feminist is to believe in, and work for, the equality of women. It's my club, too -- and anyone can join.