According to an excellent and thought-provoking article  by Sholto Byrnes, atheism is not allowed under the constitution of Indonesia. In the scope of the article, he also claims that "a declared atheist would not stand a chance of running for America's highest office". It is something that can be said around anyone with even a fleeting knowledge of American politics and society which will, more often than not, be met with agreement. The idea that a non-religious person could not be made president of the United States is, in most circles, the conventional wisdom.
The case could be made, however, that the conventional wisdom is wrong.
First, the United States has already elected presidents with no supernatural means of support. The three names – which might sound familiar – are those of George Washington, Thomas Jefferson and Abraham Lincoln. These three unelectable heathens have all merited impressive memorials in Washington, DC. All three were re-elected for second terms.
Washington, America's first president, did attend church services during his adulthood, but refused to take Communion. Told by the priest that he was setting a bad example by attending but refusing to participate, he chose to stop going altogether. So while he may not have been expressly an atheist, religion was clearly not something that weighed heavily on his mind and politics. Being religiously pious may be viewed by some as an essential characteristic of a US president today, but the man regarded as "the Father of America" was anything but.
Jefferson, author of the Declaration of Independence and America's third president, was adamantly opposed to the establishment of a state-sponsored church. It was he who wrote the Virginia Statute for Religious Freedom. This document was the primary inspiration for the First Amendment to the US constitution, which forbade the establishment of any religion by the state.
Admittedly, Jefferson was more of a deist than an all-out atheist. However, Darwin's majestic theory of evolution by natural selection would sadly not be published in his lifetime. Considering Jefferson's brilliant scientific mind, being aware of and understanding that theory may have pushed him strongly into atheist territory.
Lincoln, the man who signed the Emancipation Proclamation into law, was also not consoled by supernatural ideas.
After the death of his son, he was understandably devastated. One of the reasons for this despair was the idea that there was no "next life" after this one. He believed his son was gone for ever and dismissed any notion of an afterlife (a view that was not shared by his wife, who tried all kinds of supernatural ideas in order to feel a connection with her lost child).
Lincoln never made any public pronouncements of faith, yet is still regarded by a vast number of Americans as the greatest president the nation has ever had.
So, if one looks at history, America has already elected non-religious presidents. Whether they could be classed as atheists or not is up for debate, but certainly it is possible for someone who does not subscribe to any denomination (or, in the case of Jefferson, to be repulsed by the very idea) to be elected to America's highest office. Bringing the argument into the 21st century, how many people in 2002 would have said that America would elect as its next commander-in-chief an African American with a Muslim father and an atheist mother?
The non-religious (be they atheist, agnostic or otherwise) is the fastest-growing section of American society. To dismiss the idea that the US could never elect such a person would be to dismiss the unpredictability that makes American politics so interesting.