Any discussion of common arguments against God needs to address the use (and misuse) of the various forms of Bertrand Russell‘s famous mental exercise typically called the Celestial Teapot. Originally devised to illustrate the obvious idea that when positing something, the burden of evidence and/or proof is upon the person who is making the claim, it is a positively wonderful analogy, simply and irrefutably demonstrating its premise.
The current problem with the Russell’s teapot arises when people expand and twist the meaning and intention of it. Rather than being presented as an illustration of who has responsibility to show evidence for a theory, it is frequently presented as an example of an absurd, random hypothesis in an attempt to claim that theists are idiots. Interestingly, the people who most frequently lack comprehension of the analogy also like to call themselves “brights”. It can be argued, however, that they are more likely to qualify for the definition of athiest in the Encyclopedia Dramatica. *cough* (Sorry to my friends who are atheists, I couldn’t resist. Note that the same source also has offensively funny descriptions of theists as well).
Once the meaning has been twisted in this fashion, it, along with the currently popular memes such as the Flying Spaghetti Monster (Blessed Be His Noodly Appendage) or the Invisible Pink Unicorn (May Her Hooves Never Be Shod), are frequently used as an illustration of the so-called absurdity of religious beliefs in general. Note: For more lulz, see ED on the Flying Spaghetti Monster.
Of course, when Russell’s succinct and irrefutable analogy is perverted by lesser minds into something wholly different, it becomes something that is relatively simple to knock down. It is my argument that this misapplied use of the Teapot, as well as illustrations like the FSM and the IPU, do not adequately demonstrate the absurdity of religious belief. Before I get to that, however, allow me to insert a little discussion about names and labels.
Is the choice of word(s) used to reference an idea of a deity actually critically important? Yes and No. Yes, in that the word used may provide clues into the set of beliefs held by the speaker. But as a handy reference for an general idea/concept, not really. If you have an idea of a creator God, associated with typical attributes of same, does it really matter if you imagine it to be like a Flying Spaghetti Monster, an Invisible Pink Unicorn, a nature spirit, a maternal female, or an elderly patriarch? Does not the Pastafarian’s modification of Michangelo’s The Creation of Adam still hold the same power and meaning of the original, even as it intentionally challenges our conventional mental images?
That be what it may. The real fallacy in comparing the FSM to other popular conceptions of a creator God is that, generally, religions hypothesize the existence of God(s) in an attempt to explain or understand something about the universe, while the FSM is hypothesized exclusively in an attempt to make theists look stupid. The absurdity is immediately revealed when one considers that the FSM is a hypothesis which attempts to explain nothing about the universe. Doesn’t the very definition of hypothesis involve an attempt to explain something?

True story: One day in high school, I was hanging out with some friends. A middle-schooler, seeking to impress us with his coolness, bragged that he wore a condom 24×7. This was to convince us of the frequency of his sexual conduct and his manliness. One of us said “But how do you pee?”, and he replied “Oh, I just poke a hole in the tip”. While this little story was quite effective in enhancing his “cool factor” amongst his peers who were still in the fart joke stage, you can imagine it gained quite a different reception amongst us.

Like the middle-schooler who thought he was being cool with his tall tale, atheists believe that stories about the FSM/IPU are hilarious and sufficient proof that religious belief is stupid. Like the middle-schooler, the atheist’s peers also find the story hilarious. And like myself and my group of friends, the rest of us see a fundamental error of such magnitude that it effectively removes most of the humor and redirects the proof of stupidity away from religious belief to point directly at the speaker.
Conversely, in an attempt to explain the observed universe, religion hypothesizes the existence of a God(s) with various attributes, generally a loose collection of the highest ideals we can currently imagine. Yes, that’s right, I said observed universe. Many of us plainly see things which don’t lend themselves to logic or science. It is indisputable that many acts are motivated by feelings of Justice, Mercy, Honor, Courage, and Love. These things obviously exist, yet are not quantifiable nor provable. For a clear example, we turn to the movie Contact:

Palmer Joss: Did you love your father?
Ellie Arroway: What?
Palmer Joss: Your dad. Did you love him?
Ellie Arroway: Yes, very much.
Palmer Joss: Prove it.

Love exists; it is trivially observed. It, as well as actions based on it, apparently defy logic so frequently that the very idea is a cliche. Its very existence cannot be proven. If affixing a quantity to it is even possible, it could only be measured relative to an action taken due to it. Any neurobiologists who are thinking of raising objections to the last couple of sentences are requested to step aside; the specific asskicking of your notions is outside the scope of this class and will be discussed later. Likewise, the people who ignorantly equate love and other spiritual values to “altruism” and then proceed to show that altruism is explained by natural selection need to STFU until they can explain the distinct differences between love and altruism.
I assert that it is specifically not absurd to hypothesize a source of or a predicate to so-called spiritual values such as love, honor, and courage. Indeed, I assert that it is absurd to not attempt explanations of observable things, regardless of how well they lend themselves to scientific analysis. Unlike the FSM, my hypothesis of a creator God is, in part, a distinct attempt to explain things that I observe. I’m attempting to address the observed fact that there is more to the universe than is explainable by science and pure logic.
My theory predicts the existence of something which made a conscious decision to create the universe; I casually refer to it as “God”. This theory addresses the issue of why we are here, and subsidiary theories based upon it successfully address the existence of observed facts referred to as spiritual values (love, etc), predict that natural selection will work towards producing consciousness, as well as resolve the irreducible complexity problem of that original biological cell springing to life. In addition, these theories help me identify errors in religious teachings, doctrines, and so-called holy books. These theories are consistent with other known theories, such as natural selection; indeed, certain effects seen in quantum mechanics are predicted/required by my theory. In short, my theory is consistent with observable fact, other theories which explain observable fact, and serves to provide explanations for issues which either aren’t explained by existant theories or are at least problematic for those theories. Further, I am fully prepared to revise my theories as necessary to accommodate any future observed facts.
Because my theories actually strive to explain facts, and particularly because they remain consistent with both themselves and other known facts (not to mention other widely accepted theories), it is thus shown that my prediction of God’s existence is specifically not a case of the “Celestial Teapot”. I did not start this theory by positing God; God is rather a prediction of the theory and the hypothesis was not random or unnecessary as seen in the teapot analogy. If you think your theory explains things better than mine, fine, but you admit that it is a no more than a belief.
Some athiests, upon hearing this argument, will begin a retreat. A wise move, given that most of their attempts to show that religious beliefs are absurd tend to be directed at a version of religion which rarely, if ever, is seen in actual existence. Atheists tend to take the most obvious and arguably absurd religious beliefs, often from dissimilar traditions, and combine them all together into a straw man which is then trivially dismissed (although not before making fun of and mocking the individual believers, something which is arguably evidence that a refined morality is indeed predicated on belief in God).
No, if an atheist wishes to make an honest attack on religious beliefs without looking like an idiot themselves, they should avoid stupid comparisons to Flying Spaghetti Monsters. Rather, they should stick to the rational, logical arguments which are easily formed by pointing out inconsistencies in a given religion/denomination’s set of beliefs. Inconsistencies, especially internal ones, are always indicative of error. Study the teachings of Jesus, for example, and compare them critically to the various doctrines of (so-called) Christianity, and you’ll be left wondering what everyone has been smoking. In truth, there is more harmony between the teachings of Buddha and the teachings of Jesus than there is between the teachings of Jesus and the teachings of most branches of Christianity.
Of course, doing so won’t bring about your desired result of denying God’s existence, it will only serve to make religions stronger as the clearheaded believers within them begin to adjust their beliefs to eliminate the inconsistencies.