That's really good advice, Hopefull. I know people who are the same religion (or non-religion), who don't believe the same things. Sometimes, they believe the opposite of each other.

For instance, there are Christians who believe you shouldn't have sex before marriage. I'd guess that most Christians believe that. But there are also Christians who perhaps think it's okay, or at least, they might think it's a sin, but because they aren't perfect, that it's okay to do so. How a person interprets their beliefs is between him/her and God.