Ryan Burge, a political scientist with Eastern Illinois University and a Baptist pastor, found that 23.1% of Americans do not report any religion.
Catholics arrived at 23.0% and Evangelicals at 22.5%.
The three groups, however, remain within the error margin of each other, making it a statistical link. More than 2,000 people were interviewed in person for the survey.
The "non religious", as the researchers call it, form a diverse group of atheists, agnostics, spirituals and people who are not a specific organized religion. The rejection of organized religion is the common thread that they share.
"It's the first time we've seen this – the same questions have been asked for 44 years," Burge told CNN.
The meteoric rise of religious nuns began in the early 1990s and has increased by 266% since 1991, he said.
Burge estimates that "No Religion" will be the largest group of four to six years.
The reasons for the numbers to explodere
Experts are still debating the factors behind this wave of Americans stating that there is no religion.
One of the reasons could be internet, says Nick Fish, president of American Atheists. It is a meeting place for non-believers.
"The ease of Internet access helped to create communities where they did not feel alone," he said.
Robyn Blumner, executive director of the Richard Dawkins Foundation for Reason & Science, sees change as a generational trend of the millennial generation.
"We are witnessing the rise of a generation of Americans who are thirsty for facts and who are curious about the world," she said.
They are an under-represented group
The 10 members of the Congressional Caucus on Freedom of Thought try to represent non-theistic interests while protecting the secular nature of government.
"This growing group of Americans may feel that at least some people in Congress think they matter." says co-chair and founder Jared Huffman of California.