When I was younger, I took what my pastor said as infallible. I would defend his beliefe and beliefe in my church at all costs.. Sadly, I was just like many of these people. I could not even see the truth because I was to proud to admit I might not have truth.
I still do not think I have all truth, if I ever get to that point, I become useless to God. Because my pride has taken over.
Most of the time 'we think what I believe is all there is to believe, and it's correct. It may be correct for where the believer is in their understanding, but in time they can look back and think ' wow did I really believe that. Again it is part of our growing process.