I must take exception to a small but vital element of The Post's coverage of the retirement of Justice Lewis Powell and the opportunity it presents for President Reagan to appoint another conservative ideologue to the Supreme Court. By continually referring to pro-choice activists as "pro-abortion activists," the newspaper does its readers a grave disservice.

The term "pro-abortion" is not only inaccurate, it is highly inflammatory. It is a phrase used by the right to condemn those who seek to guarantee every woman's right to a safe and legal abortion.

If Judge Robert Bork is confirmed, liberals will have a tough fight on their hands. Bork has already made clear that he would review many of the court's earlier decisions on civil rights and affirmative action, as well as Roe v. Wade. Let's not make Bork's job any easier by feeding the fires of ignorance that continue to surround many of these issues.

-- M. Robbyn Swan 'Gushing Praise' I read with interest R. Emmett Tyrrell's recent column on Bill Casey; in that nine-paragraph article, Tyrrell told me that Casey:

was "a great public man";

"was one of the best read men in modern American governments";

"had an exquisite mind";

"was a great man";

"sustained some of the administration's soundest policies";

"saved his greatest feats for late in life"; and

was President Reagan's "wisest adviser."

It is rare that I read such gushing praise, so I combed the article to ascertain Tyrrell's criteria for greatness. I learned that Casey read many books, aided "anti-communists" and "would not capitulate to . . . inferior minds" in Congress.

With all due respect to Casey's reading habits, I would be much more comfortable with a director of Central Intelligence who could read and understand the Constitution and all laws applicable to his or her authority. It would also help if that person told the truth to Congress, regardless of what Tyrrell thinks of the intellect of that body. -- Paul K. Vickrey How Rock Music Gets Treated I was greatly disturbed by the article you published about Motley Cru e {Style, July 1}. As a Cru e fan, I understand that there has always been controversy surrounding the group's music and behavior, some of it well-founded. But what I read was unfair and a good example of how rock music gets treated in this country.

I think The Post's mention of Vince Neil's jail sentence was in extremely poor taste, being totally irrelevant to the topic of the article. The reference to his time in jail seemed to be abuse rather than something that belonged in an article about the group's music. Not only were 18 days cut from the original 30-day sentence on account of good behavior, but Vince now talks to kids' groups about drinking and driving. He was one of the first members of Rock Against Drugs. However, you failed to mention him in your March article on RAD.

I also wish to respond to what was said about the Cru e's songs. "All I Need," the ballad on the recently released "Girls, Girls, Girls" album -- about "brutal murder," as your article states -- was inspired by a newspaper story of a murder, not by some twisted fantasy in the minds of the Cru e. Songs like this are a reflection of our culture. Songwriters such as Nikki Sixx and Tomy Lee are conveying a message to America's youth. They do not condone, much less participate in, acts like the one mentioned in "All I Need." They are telling young people that we live in a world where violence occurs often and that it must be stopped. What matters is that these sensitive issues are brought to the surface, whether the proffered medium is rock music or something else.

Something I find very admirable is that the Cru e approaches things with a harsh sense of reality, on and off stage, and goes straight to the point of subjects that parents, school officials and other authority figures tiptoe around. As Cru e bassist/songwriter Nikki Sixx put it, "We take all the horrors of the world and reflect it back to people on stage. It freaks them out. But really what's freaking them out -- us or the world we show them?"

-- Kryss Speegle 'Offensive Posturing' The Post refrains, admirably, from spelling out "four-letter" words.

May I propose a similar circumspection with regard to the names of Jesus Christ and other figures regarded as deities by large portions of your readership?

Mike Sager's use of the name "Christ" as an expletive at least five times in one article {"Hunting Marlon Brando," magazine, July 5} was offensive posturing more expected in coarse girlie magazines than in any part of The Post. -- Donn B. Murphy AIDS Is Not the Only Disease Thomas McCabe is wrong {Free for All, July 4}. There is no question that AIDS is a terrifying disease, but far more people die of non-AIDS illnesses than die of AIDS-related illnesses every day. Are their causes less urgent? On any fall or spring weekend there are countless "a-thons" for this cause or that. Do they all deserve 18 paragraphs -- or even three?

On the other hand, the article about the ice-cream parlor, which McCabe complained about, was important. One of the dangers that modern cities face is the "McStandardization" of goods and services. Do we want Washington to be seen as unique because Wendy's is next to McDonald's instead of Hardee's? Small-business owners have a difficult time getting established -- no wonder so many give up and turn to franchises. The article celebrated the success of one small business, thereby encouraging many others. Small businesses add to the richness, depth and character of a city. They are vital. When I was growing up in Great Falls, the heart of the town was Buck Warner's Store. Mr. Warner listened to our awful jokes, sneaked us penny candy and -- when I was grown -- danced at my wedding. Will my children feel the same way about the local 7-Eleven? I don't think so. -- Meredith Maclay