No. While there are atheists in the US, most Americans identify as Christians.
There is no law against an atheist being president.
There is no official atheist symbol. It comes from not having an organization like a religion to establish a symbol (or greeting, or handshake, or uniform, etc). Some atheist us a script "A" in red (no dots) for their blogs, the US Military marks graves atheist graves in military cemeteries with many representative symbols. They chose a stylized Bohr atom which does have a dot on it representing an electron for atheist graves.
In US politics, it is unlikely that politicians are likely to admit to being atheist. However, some calculations can be made: Around 11% of the US population identify themselves as atheist, however around 21% of Democrat supports identify themselves as atheist so the percentage of Democratic party members is probably between those two numbers.
Probably it would be between the UK or the US. The uk is rather secular in general although they have religious communities, some Scandinavian and northern European countries have large atheist populations. In the US around 10 percent claim to be atheist but this number is growing over time.
You are not necessarily an atheist. People who read the Bible literally believe that God started us as humans and made us in his image so we were not monkeys. However, it is also possible to believe that God caused evolution which changed us from apes into the species we are today. Belief and religion should not be limited by one aspect of them. If you have faith you are not an atheist.
I'm quite sure there has, anonymously. For if they say they're atheists, of course they won't get the vote. It's tragic, but that is the present situation in the USA. In fact, I wouldn't be surprised if the US has had an atheist president. Secretly.
An English atheist is an atheist from England.
atheist
Well, sort of - the Atheist Alliance is a pressure group which campaigns for secular schooling, against the teaching of creationism and for the establishment of atheist alliance groups throughout the US. They are more a campaiging organisation than having an "action program".
*Some* Christians would. Conventional wisdom is that at the current time an atheist could not be elected president. It must be telling that no senator identifies themselves as atheist. However, 20 years ago it was common wisdom that a black man, or a woman, could not be president so things do change.
"John is an atheist, which means he does not believe in the existence of any gods or deities."
PewDiePie has not publicly disclosed his religious beliefs.