The truth is a proposition based on factual evidence.
Therefore, anyone searching for the truth has first of all ask himself: what reasonable amount of evidence would be required to make me change my mind.
The problem with many believers is that they are not on a quest to discover truth, rather their goal is much simpler: keep believing no matter what kind of evidence is shown to them.
Are you a theosophist??? How do you know that you know? How do you know that you know the truth? Well, believers would way it's faith, no need to argue though I'm curious about the evidence.