There should be NO religious test under the Constitution
This video was posted by the atheist who asked the question. Sen. Rubio's answer is the answer the overwhelming majority of conservative Christians would give. Dialog and mutual respect will begin when everybody recognizes that nobody's beliefs should be either privileged or disadvantaged under the Constitution. The playing field should be level.
That means, among other things, that it is nothing less than un-American to question the right of Christians to marshall non-religious, secular arguments in opposition to marriage redefinition, abortion, or any other issue whose position is religiously motivated. After all, the British movement to abolish the slave trade, the Abolitionist movement in the United States, the Civil Rights movement, the movement against child labor laws and virtually every other social reform in the history of the Anglo-Saxon world was put forward and advocated largely by people who were motivated by their religious beliefs.