Speaking to a suburban Detroit chamber of commerce, Santorum said the interpretation of the Constitution's freedom of religion provision has been "turned on its head," and offered his own.
"I'm for separation of church and state: The state has no business telling the church what do to," the former Pennsylvania senator told about 300 local business leaders at the Livonia and Farmington chambers of commerce breakfast.
Santorum, locked in a tough fight for the key Midwestern battleground with former Massachusetts Gov. Mitt Romney, is campaigning as the stricter conservative. He headlined a raucous rally in Flint Sunday evening where he also faulted the Democratic administration of President Barack Obama for marginalizing religion.
And while Santorum pressed his tax plan to spur manufacturing and economic growth Monday, he did not shy away during the business group breakfast from promoting a greater role for religion.
"Freedom to worship is not just what you do in the sanctuary, it's how you practice your faith outside of the sanctuary," Santorum said during the first of three public appearances across Michigan on the eve of the primary.
"All the reporters in the back will go, `Oh, there's Santorum talking about social issues,"' he added. "No, I'm talking about freedom! This is an election about freedom."
Santorum has emerged as the chief rival to Romney, who is well-financed and leads in the delegate count for the nomination but has struggled to ignite passion among conservatives.
He has benefited from the support of evangelical pastors and Christian home-school advocates, tightly-knit networks of conservative activists, who helped him in his win in Iowa's leadoff caucuses and a three-state sweep of contests on Feb. 7.
Santorum's comments come on the heels of his rebuke Sunday of John F. Kennedy's 1960 speech about his Catholic faith. In the speech, Kennedy famously said: "I believe in an America where the separation of church and state is absolute."
Santorum said Sunday he "almost threw up" when he read Kennedy's famous speech.
"I don't believe in an America where the separation of church and state is absolute," Santorum said during the interview with ABC News This Week. "The idea that the church can have no influence or no involvement in the operation of the state is absolutely antithetical to the objectives and vision of our country."