Beliefs are created from the perception and repetition of information. How they are developed and nurtured seems in little need of further explanation, and depending on one's memory and self-awareness, the genesis of a belief can often be ascertained quite easily. Every living person has developed beliefs. While certain people have convinced themselves they are utterly worthless, others have gone about donning the facade that they alone possess the true knowledge of reality. Then, of course, we have people who believe such things as rocks have souls, the man on the moon was a conspiracy, or that Jimmy Hoffa was abducted by space aliens. You name it, it's very likely that someone—somewhere—believes it.
It is the responsibility of each individual, however, to ascertain whether or not their beliefs are warranted. That is, whether or not there is sufficient reason for us to believe that which we profess to believe. “Does my belief correspond to reality?” is a question all people should wrestle with throughout their lives. Two opposing beliefs cannot both be valid. If I believe that “rocks have souls” and you don't—we cannot both be right. Either they do or they don't. Period. Granted, it may be impossible for us to know one way or the other, but that doesn't change the fact that contradictions cannot exist simultaneously.
It seems that so few people stop to examine the reasons they believe what they believe. If someone professes a belief opposed to your own, do you silently say “they're wrong” and dismiss the issue, or do you take the time to examine the reasons they may be mistaken? If you don't know why you believe something then why do you believe it? “I don't know, I've just always thought such-and-such” is NOT a good reason. We must always remember that our believing in something does not make it true. If it is true, it should be true independent of our belief, and we should have plausible reasons to demonstrate why it is. The same standard should apply to something we believe to be false.
You can believe anything you want—but you better know why you believe what you believe.