From digitaljournal.com:

This is the slogan that was put on 25 buses in Chicago this week, as a part of the Indiana Atheist Bus Campaign. The bus ads will be seen cruising all over Chicago through the month of June.
The Chicago Tribune reports that the Indiana Atheist Bus Campaign (IABC) has collected more than $10,000 USD in private donations to buy ads in Indiana and Illinois, with help from the AHA.

Charlie Sitzes, a spokesman for the group from Indiana says that “The intent of the campaign is to stimulate discussion of religion and its place in our society.”

They took the campaign from Indiana to Chicago after a similar campaign with a different slogan “you can be good without God” was reject by the public transportation authorities in Bloomington and stalled by officials in South Bend because they didn’t want the ads to be posted during the speech of President Obama at Notre Dame University.

In reaction to the Bloomington refusal, the Indiana chapter of the ACLU has sued the Bloomington Public Transportation Corporation on behalf of the IABC. The mayor of Bloomington, Mark Kruzan has denounced his own public transportation corporation, saying that he does not agree with government censorship.

“It would appear that where there is more opposition to the message that maybe that would be the place where we needed dialogue more,” Sitzes said, maintaining that the slogan is a simple fact.

“All non-believers believe God is a creation of man,” he said. “We used to have thousands of gods. Now we’re down to one. We’re getting closer to the true number.”