The strength of anti-atheist bigotry in America is undeniable. Surveys regularly show that atheists are the most despised and distrusted minority in the nation. But how exactly does this anti-atheist bigotry manifest? How do religious theists — Christians, primarily — express or act on their bigotry towards atheists? What does anti-atheist bigotry in America look like?
Deny Atheists' Equal Humanity
The most fundamental and serious expression of anti-atheist bigotry in America is to deny atheists' very humanity on some level. The worst form is to deny that atheists have any reason to be moral because morality requires gods and/or morality proves the existence of gods. This sort of hate-mongering feeds the perception that atheist can't be trusted, a frequently cited reason for discrimination against atheists.
Something very similar is expressed by saying that atheists have no reason to care about other people or can't teach their children the difference between right and wrong. These false claims feed the perception that atheists don't have the same values as normal human beings, thus causing people to conclude that atheists are at least untrustworthy if not somehow inhuman.
The most extreme expression of this is the one that is also the most literal: the idea that atheists are tools of Satan, are satanic, and/or are demonic. It's a literal form of demonization that encourages people to regard atheists as completely unworthy of all the same rights, consideration, and dignity normally according other human beings. It also helps encourage people to not give any thought or attention to anything atheists might say.
Deny Atheists Really Exist
Denying that atheists are even "real" is a popular way of denying that atheists should be treated as equals. You don't have to give any consideration to people who don't really exist or who are lying about who they really are.
Some Christians will claim that atheists can't exist because atheism requires something like knowing everything. Others will insist that atheists can't exist in difficult situations like foxholes. Whatever the specifics, the purpose is to portray atheists as unreal in some fashion — and unreal people aren't really people.
Refuse to Take Atheists Seriously
The simplest expression of bigotry is probably the refusal to give any consideration to what atheists have to say. Not taking someone seriously isn't inherently bigoted, obviously, but it can become bigotry when you dismiss an entire class of people for no other reason than that they belong to that class. Not taking someone seriously merely because they are black or female is obviously bigoted and the same is true if it's merely because they are atheists.
When this happens, it's usually in the context of dismissing atheism as a mere fad, as something pursued simply because it's "cool," and similar rationalizations. In every case, the purpose is to cast atheists generally in a negative light and discourage others from paying attention to anything atheists have to say — not because of the quality of their arguments, but merely because they happen to be atheists.
Deny Atheists' Political Equality
The political inequality of atheists in America is undeniable. More people admit that they would refuse to vote for a political candidate solely because they are an atheist than any other minority. Only one politician at the federal level has admitted to being a "nontheist" and none will use the "atheist" label.
The distrust and dislike of atheists is simply too extreme and just about all of that can be laid at the feet of preachers and pastors who keep pushing their anti-atheist messages. Keeping atheists in a position of political inequality is important if they want to preserve all of the unjust privileges Christians have managed to acquire over the decades.
Deny Atheists Social Equality
Distrust and dislike of atheists extends to the personal and social realms as well. Just as more people would refuse to vote for atheists than any other minority, more people would object to their child marrying an atheist than any other minority. People who are atheists are frequently afraid to reveal their atheism to coworkers, friends, neighbors, and even families.
Imposing social stigmas on atheism encourages atheists to remain silent and invisible. That invisibility encourages others to assume that atheists are few in number and that there is something shameful about atheism. And that, of course, reinforces the social stigmas on atheism. It's a vicious cycle which serves no purpose outside of fear-mongering and hate-mongering.
Assert Personal Superiority Through Privilege
The most insidious expression of bigotry is the assertion of religious privilege or Christian privilege. It's insidious because it's not directly about atheists; instead it's about religious believers generally and Christians in particular being treated as if they were special and thus deserve privileges unavailable to anyone else. Sometimes this comes in the form of small benefits and sometimes it comes in the form of outright supremacism.
Either way, though, it's a form of bigotry because it's based on the idea that membership in a particular class (religious, Christian, evangelical) confers a superior social, cultural, and political status over other classes. It's obvious bigotry to say or believe that whites should hold exclusive power or be treated as if their expectations should be catered to. Why isn't it as obviously bigoted to say or believe that Christians should hold exclusive power or be treated as if their expectations should be catered to?
The most extreme forms of this are known as Dominion Theology and Christian Reconstructionism. Dominionism is the Christian doctrine that Christians have a divine mandate to rule over all humanity, or at least over America. Christian Reconstructionism is a movement dedicated to "reconstructing" American law, government, and culture along Old Testament lines — with particular emphasis on the ancient laws found in the Pentateuch.
Christian Reconstructionists are relatively few in number, but they have had a lot of influence on the Christian Right and many aspects of Dominion Theology have become important for the Christian Right.