IF CONGRESS lets President Reagan appoint the person he wants for surgeon general of the United States, he will name Charles Everett Koop, a brilliant pediatric surgeon who currently holds the post of deputy assistant secretary for health. But Dr. Koop has the misfortune of being 64 years old -- just over the age ceiling for the job of surgeon general. He has the added misfortune of having political opponents in Congress who, although on record against age discrimination, are using the age limit to delay his nomination. The usual faint whiff of fakery floats over Capitol Hill as liberal Democrats try to explain the difference between their principles and their actions, and as the 68-year-old speaker of the House helps block the appointment of a 64-year-old.

Age, of course, has nothing to do with the real issues at stake. No one suggests that Koop is over the hill or in the least bit decrepit; in fact, he appears to be healthier and more vigorous than many younger men. The main issue is abortion and Koop's articulate opposition to it. He is a special target of the proabortion lobby because, prior to joining the government this year, he served on the boards of three of the most effective right-to-life groups, spoke and wrote strongly against abortion, and helped put together the antiabortion movie, "Whatever Happened to the Human Race?" The movie, and a book with the same title that Koop coauthored, suggest that abortion, infanticide and euthanasia are connected, that one leads to the other. This is, to say the least, an unpopular view among supporters of abortion.

It was said of the great Confederate calvary leader, Nathan Bedford Forrest, that he won his battles by always reaching the scene "fustest with the mostest."

Dr. Koop's opponents managed to do the same thing in reaching the media. His friends and family probably do not recognize him as he appears in the press. One observer suggests that Koop has been to appear as a "barefoot fundamentalist down from the hills," and others that he has been painted as a "neanderthal" and a "jerk."

To some extent these impressions result from deeply rooted stereotypes about antiabortionists; and to some extent they result from quotes taken out of context from the doctor's speeches and given the worst possible interpretation. Newsweek, for example, lifted one vague sentence from a Koop speech to support its contention that "he has no brief for equal opportunity for women." In fact, he was training women surgeons long before this was popular. Dr. Louise Schnaufer, one of the surgeons he trained and worked with for many years, says that "he's trained a lot of women, and I think he's all for women in medicine. . . . He's very favorable."

Similarly with Koop's religion, which has been pictured as a negative force in his life, yet is clearly a constructive one.

A Presbyterian and an evangelical, he takes his religion seriously as a guide to action. He has long worked with a nondenominational agency called MAP International to provide substantial medical aid to Third World countries. He and his wife took an orphan into their home and raised her with their own children, and he helped set up an adoption agency in Philadelphia to find homes for other children who needed them.

His approach to religion includes humility: He has told parents who have tried to thank him for aiding their children, "My surgical skills are a gift from God. Thank Him for them." And he is not superficial about religion: Acknowledging to one interviewer that he had prayed before a critical operation, he added, "I don't pray in the sense of trying to cast a magic spell. Praying doesn't necessarily mean asking for something, you know. There's a lot of value in just sitting still and listening."

While allegations of religious fanaticism and antiwoman attitudes have been used against him, the up-front opposition to Koop is based on charges that he is unqualified for the job of surgeon general. This opposition is led by the American Public Health Association, whose executive director says that Koop's position on abortion has nothing to do with their opposition to him. Right-to-life lobbyists find this hard to believe, since APHA has long been active on the proabortion side. But its charges about lack of qualification have been widely adopted by editorial writers and others, so they are worth a careful look.

The public health professionals do not dispute Dr. Koop's international reputation as a pioneer in pediatric surgery. He helped make anesthesia safe for children, did intensive work on the treatment of children with cancer, and performed difficult surgery in the separation of Siamese twins and in other cases previously thought to be hopeless. His awards include the highest that the French government bestows, the Legion of Honor.

In addition, Koop has accumulated much administrative experience in building and leading the outstanding pediatric surgery department at the Children's Hospital of Philadelphia. (This is something the public health people do not talk about; listening to them, one might have the impression that Koop is a Lone Ranger type.) And his whole record is one of much personal interest in his patients and their families. In 1978 he made a remark that sounds rare indeed for a great surgeon: "If you told me that I could never operate again, that would not bother me. But if you told me I couldn't have a relationship with patients' families I would be upset."

Given all of this, the average layperson is likely to think that we would be lucky to have Koop as chief health officer of the country. But the public health folks say that private medicine is focused on the cure of ailments in individuals, while public health is concerned more with prevention of disease in entire populations.

Dr. William H. McBeath, executive director of the American Public Health Association, recently told a congressional committee that the "almost exclusive orientation for one-to-one provider-patient relationships, so advantageous for the clinician, can actually be a disadvantageous distortion for the community practitioner committed to the broader target of equitable programming for a total population."

If Dr. Koop's reputation were that of a narrow-gauged, "cut and run" surgeon, McBeath might have a point. But Koop's whole career indicates the very opposite of that. And he has extensive volunteer experience with public health problems in Third World nations: working against a dysentery epidemic in the Dominican Republic; teaching young women of an isolated Indian tribe in Mexico to dispense antidysentery and antiworm medicines, vitamins and protein supplements; helping set up a medical school in Ghana. He also established a fellowship program to send medical students to rural hospitals in Third World nations, so they could obtain a realistic experience of international medicine and possibly decide on careers in it.

The public health professionals appear to be unimpressed with all of this, which leads one to believe that they are rather hard to please. There is also a hint of self-interest in their position; while they do not say it this way, one message that comes through loud and clear is: "This is our turf and we're going to keep it." The APHA leaders make a point of saying that never before in its 109-year history has their group opposed the nomination of anyone to be surgeon general. But this becomes somewhat less impressive when one discovers that the decision to oppose Koop was made by a 16-member executive board. And APHA president Larry J. Gordon, who started the public controversy last March when he wrote President Reagan in opposition to Koop, is not even a doctor. He is an evironmental health specialist.

All of which brings us back to the troublesome issues that underlie so much of the hostility to Koop: His opposition to abortion in general and to "selective abortion" in particular. Koop notes that his position "is not so outlandish," that it is shared by the president, the secretary for health and human services and the assistant secretary for health. "I'm always amazed to see how their statements arouse no ire," he remarks, "but things I said two years ago, I have to die for." The list of abortion opponents outside the political right includes Lindy Boggs, Thomas Eagleton, Mark Hatfield, Jesse Jackson, Mary Rose Oakar, Graciela Olivarez and William Proxmire. Koop has some good company.

But he reached his position on his own, and largely as a result of his 35 years of medical practice. When Koop entered his specialty in the 1940s, he was one of only six surgeons in the country to devote his practice to children alone. And, he says, he found himself "very rapidly becoming an advocate for children, particularly for children who are handicapped or abused." He has probably seen nearly every birth defect that can occur, including ones that laypeople find hard to imagine.

He has successfully treated infants with intestinal obstructions, ones born with no connection between throat and stomach, ones with severe problems of the urinary tract, ones with dangerous and disfiguring tumors, and even a boy with his heart outside of his chest. He has corrected problems of Down's Syndrome children and babies with spina bifida (cleft spine). In short, he has successfully treated many children who today might be aborted after amniocentesis detected their problems.

Amniocentesis is the procedure of withdrawing amniotic fluid from the womb when a fetus is 14 weeks or older. Analysis of the fluid for diagnostic purposes was first done in order to help both mother and child affected by the Rh problem, and Koop favors it when done for this purpose. But increasingly over the last 10 years, amniocentesis has been used to detect genetic problems so that the parents can have affected children aborted -- even though the extent of their handicaps may not be known. Koop and others of the right-to-life persuasion call the amniocentesis/abortion combination a "search-and-destroy mission." Koop is a markedly effective critic of it because he knows how much handicapped children can be helped, he admires the way "they have such a good spirit and don't feel sorry for themselves" and he has seen many of them contribute substantially to their families and communities.

This is not to say that Koop or any other doctor can correct all birth defects. No cure has been found for the devastating Tay-Sachs disease, which kills all affected infants in their early years. There is no cure for sickle cell anemia, although some researchers now believe they can find a remedy for it. Some are also hopeful about finding a way to prevent or cure the mental retardation that usually accompanies Down's Syndrome. Today, most Down's Syndrome children, with proper training, can learn to walk and run, engage in sports and do household chores. Those who work with them often describe them as happy and very affectionate children. Many eventually learn and hold jobs in sheltered workshops. Yet the medical literature indicates that more children are aborted for Down's Syndrome than for any other genetic problem.

Koop says that it was his concern about infanticide that led him into the pro-life movement, "so you could say i came in by the side door or the back door." He remarks that "i don't think we ever would have come to our current practice of infanticide in this country if it hadn't been for the fact that we were performing well over a million abortions a year. I think that does something to the medical profession's understanding of its healing ministry. And when you make exceptions for the unborn, there's very little difference between making them for that group and for the newly born."

Koop's opponents suggest that he is alarmist about infanticide, but he points to an impressive amount of evidence: a 1973 article in the New England Journal of Medicine in which two pediatricians reported that, over a 2 1/2-year period at the Yale-New Haven Hospital, 43 handicapped babies died after treatment was withheld or withdrawn from them; a 1973 proposal by Nobel laureate James D. Watson that a child not be declared alive until three days after birth, so that a doctor "could allow the child to die if the parents so chose and save a lot of misery and suffering"; and cases of Down's Syndrome children who starved to death after denial of simple operations to remove intestinal obstructions.

He also notes the recent case of Jeff and Scott Mueller, Siamese twins who were born in an Illinois hospital where one or more persons apparently felt it was all right to starve them to death rather than allow them to face life with serious handicaps. This, says Koop, shows that he "wasn't far off" in his early concern about infanticide.

There is also the case of Phillip Becker, which Dr. Koop calls a "tragic miscarriage of justice." In the Becker case, denial of treatment has been moved up into the teens and sanctioned by the courts. Phillip Becker is a 14-year-old Californian with Down's Syndrome whose parents have refused consent for heart surgery their son needs. Without the surgery, doctors say, he will suffer unnecessarily and probably die at an early age. Yet California courts upheld the parents in their refusal to give consent, and last year the U.S. Supreme Court refused to hear an appeal on the boy's behalf.

How about the Koop suggestion that euthanasia of the elderly will be the next slide down the slippery slope? The same arguments made for abortion and infanticide can easily be made -- and are made -- for doing in older people who have serious disabilities. Such people, Koop believes, are in danger -- "particularly if they're elderly, disabled and expensive."

But the one thing old folks have that babies lack is the vote. It is conceivable that sheer voting power will protect older people from euthanasia enthusiasts. One could say that political protection is better than no protection at all. On the other hand, it is not a firm barrier against the psychological pressures that Dr. Koop and theologian Francis A. Schaeffer spoke of in their book, "Whatever Happened to the Human Race?" They suggested that consideration of euthanasia leads "to a degradation of the elderly and, ultimately, to inferior health care for the elderly -- as well as encouraging the thought that those who do not want to 'shuffle off' quickly are somehow failing in their contribution to society."

Dr. Koop indicates that, if he becomes surgeon general, one of his chief goals will be to aid the handicapped and the elderly and to encourage more positive attitudes toward them. Liberal Democrats have long championed these groups; so if the Democrats can put down their brickbats long enough to listen to Koop, he may have a chance. The young, the old and the disabled will never have a finer or more compassionate advocate.