Chris Hammond, 22, a first-year political science student, launched the atheistbus.ca Web site this week with a goal of collecting $6,000 to run the ads on Toronto Transit Commission buses, street cars and subways, the Globe and Mail reported.
The message reads: "There is probably no God. Now stop worrying and enjoy your life," the report said.
"There's atheists that are out there. This will show them they are not alone," Hammond told the newspaper.
The move follows a similar British campaign spearheaded by journalist and comedy writer Ariane Sherine who raised $210,000 for a London transit ad blitz, the report said.
Rev. David Giuliano, moderator of the United Church of Canada, told the Globe he didn't have any issues with the atheists' message, although he would rather they say what they believe in, rather than what they are against.
"I think most of these ads ... are responding to a version of God and Christianity that is grounded in a kind of judgment and fear and guilt," Giuliano said. "I don't believe in that God either."