The atheists’ monument-building campaign is a new tactic in a long-running battle over the boundary between church and state. Having failed to persuade the courts that it is unconstitutional for a private organization to put up Christian monuments on government property, the atheists figured they should get in the game.

But building monuments to atheism from sea to shining sea is not really their goal. They figure that once atheists join the fray, every other group under the sun will demand the same privilege — including some that Christians might find objectionable, like pagans and Satanists. In the end, the atheists hope, local governments and school boards will decide that it is simpler to say no to everyone.

“It’s a very smart tactic,” said Charles C. Haynes, the director of the Religious Freedom Education Project at the Newseum in Washington, “because by countering the message, they make it unpleasant for people who want religious messages in the public square, and less likely that they will push for them.”

“I’m seeing a very messy and crowded public square, and I think we’re going to get more and more of these kinds of conflicts where people who feel they’ve been excluded want to be heard,” said Mr. Haynes, who added that he prefers crowded public squares that welcome religious diversity rather than empty ones.

The controversy in the town of Starke, Fla., began in May 2012 when the Community Men’s Fellowship, a local Christian group, put up an imposing black granite Ten Commandments monument on the National Day of Prayer in front of the Bradford County Courthouse. Two weeks later, atheists mounted a protest and sued the county, calling the monument a violation of the First Amendment’s establishment clause, which forbids government sponsorship of religion.