Atheist group the American Humanist Association (AHA) is demanding a stop to public school children participating in nonprofit Operation Christmas Child, which collects shoe boxes filled with toys, school supplies, toothpaste, and soap for needy children.

In an op-ed at the Huffington Post, Roy Speckhardt, executive director of AHA, charges that Operation Christmas Child’s goal is “converting each child to Christianity.”

He writes:

Making matters worse, this program is conducted in public schools and endorsed by school administrators, using student labor to compile boxes of toys, to which booklets are added that include evangelical tracts, sermons, and written prayers — even a pledge card that the receiving children sign to become “God’s child.” These boxes of toys are essentially bribes used to pressure poor children living in developing countries to convert to Christianity. And Operation Christmas Child isn’t shy about their efforts, bragging about the thousands of kids they’ve converted.

“Operation Christmas Child thrives on the labor of students, and the tax dollars of their parents, who have a constitutional right to expect their kids to be free from religious intrusion,” Speckhardt fumes.

According to the Becket Fund for Religious Liberty, AHA has filed a complaint in a Colorado court to prevent Operation Christmas Child from asking public school children to volunteer to collect the boxes for needy children.

“These boxes are filled with school supplies and basic hygiene items,” said Kristina Arriaga, executive director of Becket Law. “It’s heartbreaking enough that there are children who will receive nothing but a toothbrush for Christmas. The American Humanist Association would deny them even that?”

Becket reports that AHA has aimed to stop public school children from volunteering for such programs since 2013, when they sent “letters of warning” to public school districts in Colorado and South Carolina where children participated in Operation Christmas Child.