Full Disclosure: This idea is a train-of-thought spinoff from Cam's recent entry over at her blog (article link), which addresses the difference between belief and reality, or, perhaps more accurately, outward and inward truth. It isn't intended as a response, but an application of the same basic argument to a different topic. Think of it as a non-rigorous thought experiment. The entry is excellent.
More often than you would think, I have heard people make absolute statements about a reality, as if saying something is real (or true), or unreal (or false), is enough to make it so... what I like to think of as the "Abra Kadabra" fallacy. (From the kabbalistic phrase "I create as I speak".) It most frequently takes as a basis one source or another, and in the circles I run in, it's either "the bible" or "science" standing in as the source, with appropriate variations (making it an Appeal to Authority).
The problem with this statement is that there are two realities: the natural and the supernatural. Some of us prefer not to dabble in matters supernatural, for very good reasons that I'm not going to pound the table over right now. And while we can make definitive statements about natural realities through empirical study (which is what science is for), we cannot make definitive statements about the supernatural. So we can make the argument, for example, that the universe is 13.5 Billion years old (give or take a reasonably small margin of error), but we can't make the argument whether God did, or didn't, create it. I can make the argument that the bible was written by men, because, of course, it was, but I cannot say if they were inspired by angels/the divine, or whether they were suffering from schizophrenia. This is basically the root idea of empiricism.
The Divine is a personal reality, a supernatural conviction that each person must arrive at on his or her on (or not, as the case may be). So, while it is perfectly acceptable to correct those who misunderstand your belief (which is a natural force), it is not correct (nor polite), to tell them that their belief is logically untrue. Who is to say if there is or is not a God, or Gods, and which God or Gods is the "truth", when it is so subjective a thing?
In some senses, truth is mutable, but in those cases, the mutability is ambiguity. It is room to question, and questions are opportunities for growth.
Keep thinking. It's good for you, and it makes people nervous.