As much as presidential hopefuls like to whine about the discrimination they face because of their faith--ooh, people hate on me because I'm Mormon; ooh, I'm seen as a former minister, not governor--the truth of the matter is, I don't know where this alleged attack on religion is coming from. The way I see it, you HAVE to prescribe to religion in order to be a viable candidate. If I hear Hillary or Barack, the liberals, reference god or faith one more time, I will vomit.
I actually think that candidates even enjoy saying that they are judged for their faith, simply so they can keep reiterating their own religiosity and instill in the public how their holy crap smells like roses after all.
When candidates whine about religious discrimination, they are really complaining about the Christian hierarchy which gives higher appeal to certain types of Christians. But as long as you love Jesus, you still reap the benefits of the Christian advantage.
Once you move out of Christian pool of privilege, then you really feel the heat of discrimination. Americans will surely get a woman or black Christian president before a male Jew. But even so, all monotheists share the God Lover advantage, and therefore will always experience public favor over say atheists, who revoke the God Lover advantage by revoking God.
However, in terms of the presidency, it can be argued that at this particular historical moment, an atheist could one-up a Muslim...but only the context of alleged Islamo-fascism.
While the presidency is off-limits to non-Christians, Congress is slowly becoming a different matter. There is one openly-atheist member of the House: Representative Pete Stark (D-Cal), a member since 1973. And in 2007, the first Muslim Representative, Keith Ellison, was sworn in on Thomas Jefferson's Koran.
Although it is worth noting that, according to the Secular Coalition, "If the number of nontheists in Congress reflected the percentage of nontheists in the population, there would be 53-54 nontheistic Congress members instead of one."