LEAVE RELIGION OUT, SOME SAY
Estimates of the numbers of non-Christians in America vary. Some put the percentage of atheists, agnostics or "unaffiliated" at between 15 and 18 per cent of the population of 300 million.
Jews, Muslims, Hindus and people of other religions make up fewer than 10 per cent of the population.
Standing in a Hindu temple in a Dallas suburb before statues of his religion's deities, Tejas Karve says he understands why the candidates stress their commitment to Christianity. But it does leave him with a sense of exclusion.
"I think it's geared more towards Christians because that's the majority. It's incomprehensible for them (Americans) to have a candidate who's not Christian," the 26-year-old pilot, who immigrated from India eight years ago, told Reuters.
"I do believe they leave (non-Christians) out to a point."
Political professions of faith leave some unmoved.
"Why is that relevant? Who cares? The great issue is where do we stand on Medicare and Social Security and immigration ... Why inject religiosity into that?" asked Paul Kurtz, chairman of the Council for Secular Humanism.
"Are we (secular humanists and atheists) marginalised? No. Are we turned off? Yes!"
Atheists and agnostics have long been targets of the religious right who see moral decay in secularisation.
Some critics say those without a religion were singled out in the speech by Romney in which he sought to ease concerns among Republican evangelicals about his Mormon faith.
He said "freedom requires religion" - implying that it could not exist without it - and criticised those who "seek to remove from the public domain any acknowledgment of God ... It is as if they are intent on establishing a new religion in America - the religion of secularism. They are wrong."
A Pew Research Center survey last year found that 63 per cent of those polled said they would be "less likely" to support a presidential candidate who did not believe in God.
But those who say they are "unaffiliated" or atheist are very keen to cast their ballots. Pew data shows that 82 per cent of them are very or somewhat likely to vote. At 90 per cent, evangelicals are the only group more likely to vote.
