ORGANISTS LEAD lives full of contradictions. They are heard live by more people than any other kind of instrumentalists -- but usually with no aplause and the audience's back turned. Their instrument is so complex that it usually includes several keyboards for their hands and another one for their feet -- but so basic that its name is simply a Greek word meaning "instument." They play some of the world's most expensive instruments, but outside of the superstars like the late Virgil Fox and the late E. Power Biggs, they have one of the lowest salary scales in music.

Their music-making tends to be a solitary activity, except when they are performing in their alter egos as choir directors. But they seem to be a gregarious bunch in their spare time -- as 2,200 of them will get a chance to demonstrate in Washington this week at the national convention of the America Guild of Organists.

The organ is older than Christianity, and for most of the history of Christianity it has been the primary musical instrument played in churches. And it has more to offer, not only in its repertoire (which is older and more abundant than any other instrument's) but in sheer volume and variety of color. But most audiences, when they hear an organist, are thinking about something else -- Heaven, for example. "Some congregations only notice the organ when it's bad," complains one Washington organist. "They ask me, 'Why don't we sing the good old hymns?' when I am playing them chorales that are several centuries older."

When organists complain, they usually talk about long hours of solitary work (a common problem among keyboard artists), about congregations and committees and pastors who don't understand or appreciate what they are doing -- above all, about money. But they sound, on the whole, like people whose work is also their pleasure.

"The trouble," according to Eileen Guenther, "is that we enjoy what we're doing so much, we're willing to do it for less money . . . It's neat to be able to do what you really like, and hopefully some day we'll be able to make real money at it."

Guenther is the minister of music (alias organist and choir director) at the Foundry Methodist Church, where, she says, "we have a bad organ but a really good music program." She is one of a handful of organists in the Washington area who earns $20,000 a year or more (but not much more). Even supplementing her salary with a weekly radio program on WGMS, classes at George Washington University, recital performances and private students, she faces a serious economic problem: as a professional organist, she sells something that many others are willing to give away.

She is also the general chairman for the guild's national convention, which will open tomorrow at the Capital Hilton and run through the week at churches, campuses and concert halls all over Washington. Founded in 1896 to establish and maintain standards of education, repertoire and performance for the organ, the Guild is now under pressure to take on some functions of a labor union.

One problem is that most organists must negotiate with churches, which are often reluctant or unable to pay a living wage and sometimes expect people to work for the love of God. Another is that there is seldom more than one member of the guild working at a particular location. When a symphony orchestra goes on strike, people are apt to notice. If an organist goes on strike, it attracts less attention -- particularly if the pastor has a niece who plays the piano and can pick out "A Mighty Fortress Is Our God" on the organ.

Maureen Jais-Mick is one organist who has become involved in salary discussions: "When I talk to churches about salary and they ask me how much they should pay," she says, "I say that if this is a full-time job, they will want to pay their professionals at the same level as members of the congregation. They don't want to hear that, particularly in places like Potomac, but it's really true."

Her job at Christ Lutheran Church is part-time (20 hours a week, $8,500 a year), but she says there is plenty of work for a full-time musician in a musically active church. Like most organists, she is bothered by members of the congregation who think the organist works only for an hour on Sunday -- a few more hours if you count rehearsals:

"A fair amount of time is spent simply in preparation. That means keeping up with what's happening in church music -- new music, new books on the subject. We Lutherans now have a new hymnal, so that means there's a great deal of studying being done on Lutheran hymnolody and Lutheran liturgy. You have to keep on top of what your job is going to be and knowing what's happening all over the country and all over the world and what the latest word is in musicology. A good deal of time is spent learning the music for organ, learning and teaching the music for choir. Then, there's an awful lot of secretarial work, because you're managing a budget. If you have a concert series, you spend a lot of time planning concerts and auditioning musicians. There's a lot of correspondence. You have to go to a lot of meetings and serve on committees. We have to plan our liturgical services four to six months in advance; you know, you read all the propers and try to figure out what anthems will go with them. You can start in the summer and you know what the readings will be all through the winter, and it's a challenge.

"And, of course, if you're really interested in what you do, you have to get involved in the life of the church. If the parishioners support you, you have to be prepared to support them in their activities. I participate in a certain amount of fund-raising; I visit the sick, go to garage sales, try to help people when they are in trouble. There's a lot more happening than what you hear on Sunday morning."

To become a fully qualified organist and choir director requires considerable training. Ken Lowenberg of Chevy Chase Presbyterian Church, for example, took four years of undergraduate college, 2 1/2 years more for a master's degree and an additional year at a special college for church musicians. He holds the degree of fellow from the American Guild of Organists (FAGO), which is generally considered the equivalent of a doctorate in performance and theory.

Economically, he is a member of the Washington organ elite; he earns a salary of $22,000 a year and raises his income to about $26,000 by giving private lessons and playing at weddings, funerals and concerts. His church is one of the musical powerhouses of the area, with no fewer than seven choirs, a concert series besides its religious music program and an annual Bach marathon every spring. His income, he says, allows him to have "a car and a house -- no luxuries but comfort. When I compare myself to other organists, I think I'm not doing too badly. But when I compare myself to doctors, lawyers and other professionals, I don't feel so prosperous."

Other organists feel even less prosperous, and with reason. Full-time organists may earn anywhere from $10,000 a year at a small church in New England to $40,000 at a few large churches in Texas. And there are a lot of part-timers who earn nothing at all or much less than $10,000. It is probably fair to say that most of the guild's 18,000 members are professionally happy and economically depressed.

Carol Martin, for example, is a free-lance organist and choir director, conducting choral rehearsals and Sunday services for fees that are sometimes as low as $50. At that rate, she has plenty of work. "I'm booked through August already," she says, "and there were no more than eight Sundays in the past year that I haven't played somewhere."

But $50 a week is not quite a living wage. "The problem," says Martin, "is an overabundance of unqualified musicians who are willing to do it for less. And people are willing to settle for less because they don't know any better."

Bob Jones, organist at Berwyn Presbyterian Church in College Park, a small congregation with a proportionately small budget, has found a modus vivendi. Fired from his last job after a disagreement with the pastor, he was offered his present position and after some negotiation, he decided "they were paying me as much as unemployment was going to pay and I'd rather be doing something." Later, he also took a part-time job as secretary at the same church, with two salaries: $8,000 for his musical work and $6,000 for his secretarial work. So now, he says "they're underpaying me for two jobs."

Still, adopting the "money isn't everything" philosophy common among organists, he says he is essentially happy: "The pastor here doesn't worry about the music detracting attention from him, and we work together harmoniously. And whenever I seem to get discouraged, someone says something good about the music and it's all right again."

Maureen Jais-Mick works in one of the few churches where the organist can hear applause on Sunday mornings, and she has mixed reactions. "In my church," she says, "the congregation does applaud the postludes, but that's not what you're there for; you're not up on a stage. You try to reach the people in the congregation and if you've done your job right, people don't get restless. If you try to take precedence over God, you're doing your job wrong."

Whether they are applauded or not, organists are convinced that their work has a market value as well as a spiritual value, and they are looking for recognition of it. "People do shop around for churches," says Eileen Guenther. "We have people coming long distances to a place downtown with no parking, and many of them tell me that the music is one reason."

Economic questions are still a new preoccupation for the organists' guild. Most of the agenda will be more traditional when the convention opens tomorrow at the Capital Hilton for a week of workshops, lectures, organ tours, concerts and recitals. Organ music will be sounding all over town through Friday evening, generally for capacity audiences. Among the dozens of musical events, only two are open to the public: a concert for organ and orchestra, with members of the National Symphony, tomorrow night at the Kennedy Center, and a program for chorus and orchestra Friday night in Constitution Hall.Otherwise, the audiences will be packed solid with visiting organists: the most audible and least visible soloists in all of classical music.