At the end of the day, I don't care what people believe. In general, so long as their beliefs don't negatively impact me, I figure they can feel free to think what they want.
Unfortunately, a non-trivial percentage of "believers" seem to want to convince everyone else of the "rightness" of their beliefs. In principal, I don't have a problem with this, either. I like to explore new ideas. So long as people are respectful in how they seek to push those ideas, then "cool." Unfortunately, so many "believers" try to convince me of their "rightness" using dubious, and often easily-refutable, facts.
I take it as somewhat disrespectful to try to push your beliefs using factual errors. I take it as you saying to me, "I think you're too dumb or too lazy to verify this information." I also take it as them lying to me. I don't tolerate lying very well.
The other option is to believe that they're simply in error. However, if an error is easily corrected by referencing a cardinal document, a few Google searches or whatever, I have to wonder why they're in error. Is it stupidity? Is it laziness? Is it willful ignorance? None of these are good options. None of them leave me any good avenues for preserving any respect for their arguments.