Under the city’s rules, any group was allowed to apply for as many as 14 spaces. Because Mr. Vix had seven people applying for the maximum amount, they were more likely to get the spaces in the lottery.

“Rather than use it to put forth a message of their own, they’ve really shown that their goal is just an effort to take something away rather than give anything to the community,” Mr. Jameson said. “They’re trying to censor something that the community has clearly shown it appreciates.”

Adding to his unhappiness, he said, is that none of the atheist applicants live in Santa Monica. (Mr. Jameson himself lives a few miles away, but attends church in the city.)

“The idea that religious speech is less protected than other free speech is an attack on the First Amendment, and the attempt of these people to block us is a real attack on our rights,” Mr. Jameson said. “This is just our way of saying ‘Merry Christmas.’ ”

Mr. Vix said he had encouraged the atheists to leave some of the spaces blank. If they put up as many messages as the Christians had, he said, there would be a backlash, and he predicted that the city would cancel the December tradition altogether. He also said the atheists had been trying only to receive the same amount of space that the churches had for years.