Thank goodness more and more parents are sending their kids to Sunday school {front page, Dec. 20}. I was beginning to despair that an entire generation had lost an important part of our cultural history. I'm not a religious fanatic, but I am a docent at the National Gallery. Each week I give tours to schoolchildren, and most tours include one or two religious paintings. Though the children come from public and private schools all over the metropolitan area, I am consistently surprised and saddened by what they don't know.

They know their primary and secondary colors just fine; some are conversant in Greek mythology or the French impressionists. But in too many cases, questions about religion are met with dead silence. I'm talking pretty basic stuff. I'd like to tell them that halos in a 15th-century Nativity scene are painted with real gold, but first I have to explain what a halo is. "What's that yellow hat on their heads?" one child asked.

One of my favorite pictures is "The Youthful David" by Andrea del Castagno. I rarely get to talk about artistic techniques, such as the masterful use of foreshortening. I'm too busy telling the story. Perhaps one child knows Goliath's name, but most sit wide-eyed as I tell of David's slingshot and his triumph over the Philistine.

Another favorite is Rubens' "Daniel in the Lions' Den." All are excited by the snarling beasts, but it's a rare child who can tell me how Daniel got in that predicament or how he got out. Most children have only a vague idea who the prodigal son or the good Samaritan was.

There are exceptions to this sad tale -- primarily students from parochial schools. I'm certainly not suggesting such schools for every child. But I do hope the families quoted in the article are starting a trend.

Please, parents, get a book of Bible stories for children and read them to your kids. Don't assume that they are picking it all up out there somewhere in our secular society. They're not. You might even want to plan a trip to the National Gallery specifically to see the religious pictures. The old masters knew how to paint a story so that the illiterate masses would understand. They still tell a powerful story and, God knows, we still need to learn. JOYCE GARBER GAMSE Washington