In total, seven large billboards reading “Imagine No Religion” or “Praise Darwin: Evolve Beyond Belief” will be erected at locations around the city.

The billboard designs feature the phrases written in calligraphy against a stained-glass window background, like those found in churches.

The signs are part of a campaign by Freedom from Religion Foundation, which has placed similar billboards in over 10 states and more than 30 cities.

Currently, Imagine No Religion billboards are up in Indianapolis and suburban St Louis. Next month, the group plans a “billboard blitz” in Las Vegas.

In addition to billboards, the foundation currently has 75 large bus displays in San Francisco that read “Imagine No Religion” or Mark Twain’s “Faith is believing what you know ain’t so”.

There are another 200 interior signs around the city with quotes by famous non-believers such as Richard Dawkins and Butterfly McQueen, who played Prissy in “Gone With the Wind”.

“This is an attempt at balancing the media messages of religion aimed at believers with some percentage aimed at unbelievers,” said Paul Pearson, a member of the Michigan FFRF. “Letting unbelievers and those with healthy skeptical doubt know FFRF exists can give knowledge and comfort.”

A recent report shows that the number of non-religious Americans, or “nones”, is on the rise. Nones now make up 15 per cent of the total adult US population and the statistic is even higher among young people.

The percentage of Nones has increased from 8.1 per cent of the adult population in 1990 to 15 per cent, according to the findings from the American Religious Identification Survey.

Freedom from Religion Foundation reports having a membership of 14,000 atheist and agnostic members across the country, including over 400 in Michigan.