Our current opnion on any matter is the opinion that we view best reperesents our core values. Experience (the gaining of facts), and logic (the processing of facts) can shape our opinion without disrupting the core values by modifying our view of what is the best representitve given available data.
Religion IMHO, is just a logical mistep, albiet a very persistant and powerful one.
In the end logic and experience can only go so far, the core values can't be changed.
So if we allow for the same core values, logic and experience are the only way to go. For increasingly different core values, the ability for logic and experience to change another's view is decreasingly effective and the rightness of either party is less and less able to be argued.