As an antitheist, I believe that faith in God is a poisonous and contagious disease that threatens the well-being and continued existence of the planet and the human race. This is not an extremist position, but simply the logical conclusion one comes to when theism is evaluated critically instead of given an undeserved exemption from reason, evidence and common sense. While thousands upon thousands of pages could be (and have been) written proving this to be the only logical and moral conclusion, for purposes of brevity I will confront the short list of easily refuted counterpositions provided by people who do not consider themselves antitheists.
(1) THERE’S A GOD.
The most common argument against antitheism is, unsurprisingly, the least substantiated. Simply put, it couldn’t be any less substantiated because it isn’t substantiated at all—not by evidence, reasoning or anything else. You need not have any faith that there is no God any more than you need faith to not believe in Harry Potter or Darth Vader. If something cannot be differentiated from fiction in any way, it is—until otherwise substantiated—fiction precisely. This standard is a time-proven method for adults to tell the difference from real life and cartoons. To believe Jesus was the son of God and not believe in, say, Spongebob Squarepants is to take a child’s cartoon more seriously than a text that million of people believe is true—a very dangerous double-standard.
Evaluated from a strictly rational position, nobody of normal adult intelligence would make the mistake of thinking a religious text about God was fact. The claims of these books are more outrageous than those of most fictional texts, and they are riddled with more logical inconsistencies than most Hollywood movies. People do not generally believe in these texts because they are asking hundreds of logical questions and getting the wrong answer every time—it is much more likely that they are simply deceiving themselves. Many theists claim “personal experience” with God, but illogically rule out the most obvious and only substantiated explanation: that they are delusional. Followers of conflicting faiths also share similar but contradictory experiences, from which you can deduce that it would be impossible for every one of these experiences to be a product of divine revelation. Since, aside from being incompatible, these experiences are not particularly unique there is nothing to differentiate one perceived instance of revelation from others that couldn’t possibly all be true. All legitimate scientific studies of prayer have shown that it has no apparent external effects, and the perceived results of prayer are easily explained by the human ability to attribute causation to any correlation. Theists are only capable of citing “personal experience” as an evidence of God if they subscribe to the idea that they have particular immunities to self-deception that humans of other faiths don’t have. This is an arrogant and untrue assumption that no doubt carries the potential for unnecessary conflict.
The idea that believing in God is a “safer” position, through Pascal’s Wager, is also fallacious because it assumes that God could only reward people for having blind faith. Since a God that rewards people for being skeptical as opposed to believing out of fear is equally unsubstantiated, this is not mathematically sound. Also, considering the countless existing conceptions of God the odds of you picking the right one are literally millions to one—and that’s operating on the unsubstantiated assumption that God exists at all.
(2) IT IS BAD TO CRITICIZE THE BELIEFS OF OTHERS.
There is a school of thought that the problem is not religion, it is intolerance. This perspective usually manifests itself in blatantly hypocritical statements like “believing that other people’s beliefs are bad is bad”. Clearly, the characters who fall in this camp are incapable of self-evaluation. This school of thought ignores the fact that most religions include beliefs that are inherently intolerant to both other faiths and a lack of faith.
Some religious types even compare antitheism to racism, while a more accurate analogy would be that antitheism is like being opposed to racism. Few of these same people would argue that racism is harmless just because it is based on beliefs, or that since most racists don’t kill people they don’t contribute indirectly to racial violence and repression. Clearly, not all beliefs warrant absolute tolerance. This is just another example of religion getting held to different standards than other institutions. And to anyone who thinks comparing religion to racism is unfair, please do at least some research on The Ku Klux Klan, The Holocaust and the pro-slavery verses in The Bible and Q’uran.
(3) RELIGION MAKES PEOPLE MORE MORAL.
Simply not true. Prison populations are exceedingly religious, as are the more barbaric countries in the world. The United Nations Intelligence Report in 2005 evaluated countries by life expectancy, adult literacy, per capita income, educational attainment, gender equality, homicide rate and infant mortality. The highest-ranking countries were also the most secular, whereas the lowest-ranking countries were generally theocratic in nature.
This is not surprising to anyone who has read the books of the central monotheisms, which encourage killing and condone rape, genocide, sexism, child and spousal abuse and slavery. These books are generally referred to when something cannot be justified by secular means. Good will towards others requires no such rationalization, but certain atrocities do. This is why religion functions much more thoroughly as a tool for evil than a tool for good.
The argument that killers like Stalin and Mao were atheists is very common on this point of contention, ironically coming from Christians who also argue that you can’t judge Christianity based on “a few individuals”. Maoism and Stalinism were religions like the Abrahamic religions because of their demands for servitude and blind faith. Whether or not they were theistic religions is debatable. Stalin, Mao and Pol Pot did not call themselves "God" but if we're really going to examine what theism is we're going to have to get past the myriad of semantic problems to the actual nature of the beliefs ("pantheism", for example, uses the word "God" as a metaphor for The Universe but ideologically it is essentially atheism). These religions are called “cults of personality” because they are based on the worship of human leaders. No doubt theism can center around a mortal human—otherwise Christianity would be atheism, and it isn’t. There is no question that North Korea's religion is theism because their president is not Kim Jong-Il but his dead father Kim Il-Sung—the supernatural element makes that easy because it puts it in the same category as Christianity. With other “atheistic” dictators it depends entirely on how broadly you define “God”, but we do know they didn’t kill _for_ atheism the way religious dictators killed _for_ religion which makes the role atheism played in their regimes completely different and the analogy flawed.
No doubt people can find reasons to kill each other without religion, but when your best defense for something is that it isn’t responsible for _all_ the evil in the world you should probably reconsider whether it’s really that great. The Holocaust, The Crusades, The Inquisitions, Islamic terrorism, witch trials, honor killings—theism is still responsible for that. Some would argue that science is responsible for death, too, but science is necessary and contributes substantially to the health and well-being of humans everywhere. When people die because of religion, they are dying because of something that is completely unnecessary. It isn’t just the fault of the ones holding the weapons—if millions of other theists didn’t perpetuate the continued existence of these mentalities they wouldn’t exist. So the blood is on all their hands.
Is theism the biggest problem in the world? I think that’s the wrong question, because it assumes it is something distinct from other problems. Racism, sexism, homophobia, slavery, genocide, rape, war, child abuse, mental illness, ignorance, hypocrisy—the list of bad things exacerbated by theism is endless. To support theism is to support every great evil in the world for no sane reason.