Church membership in the United States is almost but not quite keeping pace with population growth, according to the just published 1979 Yearbook of American Churches.

Total church membership increased seven-tenths of one percent during 1977, the most recent year for which statistics are available, according to the volume. During that same time, population increased by eight-tenths of 1 percent.

As in years past, the most substantial growth was recorded by theologically conservative churches, with the Church of Jesus Christ of Latter-Day Saints (Mormom) leading the list with a 3.95 percent increase.

The nation's mainline Protestant churches - Episcopal, Presbyterian, United Methodist, Lutheran - again reflected declining membership. But the rate of decline has slowed considerably from what it was five year ago.

The yearbook, published by the National Council of Churches in New York City, provides the most comprehensive statistics available on institutions of organized religion. This year's volume contains data on 222 religious communions - Protestant, Orthodox and Roman Catholic.

According to the yearbook, the total number of ordained clergy increased overall by 11,132 during 1977, thus creating problems for many Protestant denominations that already have a surplus of clergy. The opposite situation prevails in the Roman Catholic Church.

Constant H. Jacquet, yearbook editor, said the clergy surplus is particularly acute in the United Church of Christ, the United Presbyterian and Episcopal churches, with other denominations "approaching oversupply."

He predicted that the situation "may signal the continued growth of nonstipendiary clergy and of ordained clergy working in allied professions, such as chaplaincies or counseling."

But, according to the yearbook, black Protestant denominations face a serious and continuing clergy shortage. While there has been some increase in the number of black seminarians in recent years, the yearbook states that blacks constitute only 4.1 percent of the total seminary student population.

The number of women preparing for the ordained ministry has climbed. Since 1972 the number of women seminarians has increased 167 percent, compared to a 26 percent increase in male students during the same period.

But many of the women face difficulties when they graduate. According to the yearbook, fewer than half of the 222 religious bodies surveyed ordain women. Of those that do, women comprise only 4 percent of the clergy, with very few of them in major pastorates.