A whole group of people -- Those who refuse to get nervous about shopping -- know that as Christmas nears, so does the Christmas carol.

Told in childhood that our role in the choir was to fill the ranks, not to swell the song, we are the ones who could not stay in tune. The purpose of song is to praise God, not to scare him, as one choir director explained. He went on to suggest that those of us sliding up and down the scales should let our hearts sing the song, and mouth the words.

But it is embarrassing to go through the Christmas season with your lips miming "Hark, the Herald Angels Sing," and it is time to stop such nonsense. Christmas is the season of good will toward men -- even those who sing off key.

If you can sing, give a caroling party and invite a few people who can't. If you can't sing, give a caroling party and invite a few people who can.

A caroling party should be large enough to make a respectable showing, but not so big it looks like the University of Michigan marching band at half time. A dozen people is about right. They provide the voices; you provide everything else, from song books to a pitch pipe so that at least you start out on the right note. (Veneman Music, 1150 Rockville Pike, Rockville, has them for $4.95. Check the Yellow Pages for a music store near you, and don't forget to pick up a handful of sheet music or caroling books.)

Have Christmas music on the phonograph when the guests arrive. Among traditional albums:

* On Christmas Night, Christmas carols sung by the Choir of King's College, Cambridge (Argo-ZRG-5333, $9.49 at Record & Tapes Ltd.).

* Christmas Jubilee, by the same choir (London JL41047, $5.99).

* Christmas at St. John's College, Cambridge (Argo-ZRG-782, $9.49).

And then there are the less traditional. One man feels that it just isn't Christmas until he listens to Christmas With the Chipmunks with Alvin, Simon and Theodore shrilling "Jingle Bells."

The caroling should start as soon as everyone is assembled (do not serve drinks at this point, or you will never get everybody out). If someone is hopelessly late, leave a note with your route tacked to the door so they can catch up.

In choosing the route, take into account which neighbors are likely to throw praise and which an old shoe. Five or six houses, with a short medley at each, should leave everyone feeling jolly but with enough lung power left to finish out the evening.

The leader carries not only the pitch pipe but a lantern: a Dickensian touch, but a practical one since many houses are poorly lit and you do not want your Christmas carolers to wind up in a heap. (W.S. Jenks & Son, 738 7th St. NW has several varieties of kerosene railroad lanterns, $13.98 to $24.95.)

If you have more money than willing friends, you might prefer to hire someone else to provide the Christmas music. Baroque Chamber Music (544-4944) will play 18th-century Christmas music for recorder, flute, harpsichord, cello, violin, etc., $300 and up an evening, depending on number of players.

Having been merry, it is time to eat and drink. Food should be simple, something that you can set out before you leave, like a roast turkey with buttermilk biscuits for sandwiches, or a ham with mustard fruits. For drinks there is an old Virginia recipe for eggnog in The Williamsburg Art of Cookery:

"Beat yolks of 12 eggs well. Add 2 1/4 cups of sugar and continue to beat well. Add 1 quart of good brandy, 1 pint of Jamaica rum alternately and slowly. To this add 3 quarts of heavy cream and fold in half of the beaten egg whites. Beat remaining 6 egg whites very stiff and add 1 cup powdered sugar. Then stir lightly into this 1 quart of cream and fold this mixture into the other ingredients. Let stand 6 to 12 hours in a cold place before serving."