(Adam asked me what the point was of posting the long list of gods in a previous post, and if that proved all religions false. Rather than wrestling with the tiny reply box, I thought it would be best to reply in a blog post. My reply is as follows.)
That all depends on how one defines "true."
If God is simply a human subjective experience brought on by prayer, meditation, singing, worship, etc., an experience that exists only in the mind of a believer, then, yes, all religions are "true" in that sense. But if that is faith, by that measure, virtually any claim could be considered "true" given those standards. But I would argue that religious claims of "truth" extend beyond the mind of the believer. Intercessory prayer alone indicates that gods are called upon to intervene in reality. When believers make claims that a god is tinkering with reality--reality being an empirical claim--the skeptics have tools to determine whether that claim is true or false (see Karl Popper's Falsificationism) .
Therefore, I think the abridged list of gods, which illustrates the vast array of religious diversity, mythology, and innumerable sincerely held beliefs declared over several millennia, constitutes a very good reason not to believe that any of them are true. All empirical claims of gods are unfalsifiable. They all can’t be true, but they all can be false.
In fact, the immense multiplicity of religious beliefs that countless adherents so devoutly and fervently adhere to with unshakable conviction ultimately exposes faith as an entirely unreliable epistemological system for justification and knowledge.
For example, let’s look at Pascal’s Wager, which argues that humans are betting with their eternal lives whether God exists or not. Pascal says it’s better to bet on God because if you win, you win big; if you lose, you lose everything. This implies real-world (or other worldly) consequences, which is an empirical claim, and not a subjective "truth" of wishful thinking. Pascal equates this wager to a coin toss, e.g., God exists or does not exist. This is Probability theory with two possible outcomes—1:1 odds in theory.
Now take a look the list aforementioned list. The interminable list of gods and supernatural entities renders Pascal’s Wager considerably more problematic, and the probability of choosing the correct god, as well as the correct brand of religion under a particular god, is baffling at best. Within Probability theory, the chance of winning Pascal’s Wager more closely resembles state lottery rather than a simple coin toss.
That being said, I doubt that showing this list of gods to a “true believer” entrenched in dogma would affect their beliefs whatsoever. But what we know is people take their religious beliefs seriously, whether it is monotheism, polytheism, animism, or anthropomorphism. Most humans who ever existed were probably polytheists or animists. Monotheism is a relatively new concept within human evolution.
So, the question that someone interested in the truth has to ask is: on what basis are religions deemed true or false in the past and in the present? Today, Eastern, Middle-Eastern, and Western religions have dedicated adherents who are equally devout, and the “truth” of each of their religions is taken on faith. To me, this seems problematic. There’s not a shred of evidence for any of the gods. There’s interesting and sometimes captivating myths, but no evidence.
If they are employing faith as an epistemological system of justification, and there seems to be an infinitely vast array of answers to the very same question, one would have no choice but to conclude that faith is a failed epistemology.