If you think Sunday school is just for Christians, think again.

Each Sunday morning, thousands of children show up in classrooms at houses of worship across the Washington area. But instead of learning about Jesus Christ, the Trinity and stories from the New Testament, they study the Koran, the Bhagavad Gita and the Torah. They learn about Indian culture, memorize Arabic or Hebrew, or explore an atheist path to ethical living.

It’s all part of a rich pastiche of lessons developed over the decades for the children of those in non-Christian faiths — including Jews in Cleveland Park, Muslims in Sterling, Hare Krishnas in Potomac and humanists on 16th Street NW — that take place on the traditional Christian day of worship.

“That’s when people are available and that’s when they’re used to dealing with matters of faith and philosophy,” said Roy Speckhardt, executive director of the D.C.-based American Humanist Association. It recently announced that it wants to dramatically expand its “secular Sunday schools” from a handful to all of its 125 chapters around the country.

In the Hindu faith “there is nothing in the tradition which mandates Sunday as particularly sacred,” said Vineet Chander, a spokesman for the Hare Krishna movement. Formally known as the International Society for Krishna Consciousness, it is a branch of Hinduism.

But in the United States, Sunday “becomes a practical choice,” Chander said.

For many minority faiths, Sunday education involves teaching children about more than just their religion. It is a time for immersion in language, culture and tradition that children probably will not encounter outside their families and their religious communities.

At the Hare Krishna temple in Potomac, “we try to include the culture along with the religion,” said teacher Vidarbha Suta. Children learn about Indian life along with delving deeply into their faith.

The Jewish faith offers Sunday school, even though its Sabbath runs from sundown Friday through sundown Saturday. For Reform and Conservative synagogues, as well as some Orthodox ones, Sunday mornings are a time for younger children to learn about their religion and the Jewish culture in preparation for their bar or bat mitzvahs.

Hundreds of children, from kindergarten through seventh grade, spend their Sunday mornings at Washington Hebrew Congregation’s Cleveland Park synagogue or at its suburban center in Potomac. There, they spend half their time learning Hebrew and the other half on Judaic studies, such as Bible stories and Jewish history, Rabbi Joui Hessel said.

Sunday religious programs for Muslim children are also a well-established tradition in the United States. The All Dulles Area Muslim Society (ADAMS), one of the largest mosques in the D.C. area, offers morning and afternoon sessions for 500 children at its Sterling location, ADAMS spokesman Rizwan Jaka said. Along with studying the Koran, the children learn Arabic, socialize, play sports and do community service work. The usual Islamic day of worship is Friday.

And now humanists have launched an ambitious effort to expand their Sunday school programs. Pointing to a 2006 poll, which estimates that between 14 and 18 percent of Americans consider themselves atheists, agnostics, humanists or not religious, humanists see a big demand for their own education programs.

In May, the American Humanist Association announced the launch of the Kochhar Humanist Education Center in Northwest D.C. to develop a curriculum for the humanist equivalent of Sunday school.

Children, and eventually adults, will learn about the history of secular humanism; the basics of critical thinking; values and virtues like humility, empathy and courage; the basics of evolution; conflict resolution; human rights; and the separation of church and state.

They’ll also receive a solid grounding in the world’s religions, said Bob Bhaerman, education coordinator for the Kochhar center.

At the Washington Ethical Society, a humanist religious community on 16th Street NW with about 300 members, Sunday school is already well established. Children start in nursery school and progress through high school.

The overarching goal: “Children learn to be kind and fair and get an opportunity to create a better world for all,” director Peggy Goetz said.

This week, the younger children started class by gathering in a semi-circle. Adam Bogomolov, 9, lit a candle, a bell was struck and the class recited its creed:

We are an ethical community — a community of open minds, caring hearts and helping hands. Together we work to bring peace and justice to the world.

They made bookmarks for Father’s Day, then worked in the garden, where they are growing tomatoes and peppers as a way of learning about the interconnected web of life, Goetz said.

Michele and Jeff Kuhn joined the ethical society six years ago. They said they want their children — Michelle’s 15-year-old daughter, Sarah Strohminger, and their two-year-old son, Jonathan — to have a humanist religious education.

“No Sunday school was never an option,” Jeff Kuhn said. The core values of their Sunday school are the same as the core values of any religion, he said, adding, “It’s about love and love of community and justice and being a part of a community.”