Not agreeing with each other is not a reason to dismiss an entire way of thinking. Look at us! Two atheists disagreeing!
There is an important difference, though.
We base our opinions, thoughts, perspectives, and experiences on worldly happenings, observable truths, testable hypothesis, etc.
Religious worldview and "rules" are governed by the same text and same governing body (i.e. the Vatican in the case of Catholics), so they should be on par 100%. A Catholic Church on one street should have the same worldview as the Catholic Church down the street from them, or the one an entire state over.
If they don't, they are either making up their own interpretations of the same text, doing whatever because it's convenient for them, or they don't take their religion seriously enough.
I mean, if they literally believe that God gave them a set of rules to live by, or that God appointed someone to interpret those rules for them, then changing those rules would be failing their test of faith; which is critical, since faith is perhaps the most important thing that God wants out of them, second to begging for forgiveness.
That's why the idea of religion and religious organizations is silly beyond belief.