First of all, there's a difference between to believe and to believe in something. This is a quote I found. Hope it helps.
To believe in something or somebody means to have faith in them or in it and this requires a long term relationship. For example, you can say I believe in miracles which means you think that in general it is possible that miracles happen.
To believe + object describes a more concrete situation, usually it's a single action as in our sentence.
If your friend calls you tomorrow announcoing I've just won 3 million dollars in the lottery! you simply might reply I don't believe you which means you don't think that this particular statement of his is true.
from:
http://www.english-test.net/forum/ftopic3572.html
I personally assert that to believe in something is a motivation. It motivates you to acquire certain goals, gives you hope and expectations, lift your confidence up, but it doesn't. DOESN'T. distinguish you to non-believers.*by putting non-believers, I don't mean to connect this to some kind of spiritual belief or such thing. They literally mean anyone that doesn't believe in whatever you do believe in (e.g. hard work, luck, the importance of facebook, the doomsday, the positive of stalking -- now it's getting personal, haha...)
My point is to really underline action as the fruit of an idea. Frankly, I don't care about what you believe in.
You can believe in, you know, tarot cards, whatever, I don't care. Not mainly because I'm a self-centric bitch, well that may be a part of it, but yes, what you believe in per se won't affect me and my life. I am not disturbed by your confidence in tarot cards. And yes, what you believe in and what I believe in don't make us different until you/I practice your/my belief tangibly. In this case, I would be mad if you forced me to walk straight on my way to school because according to your tarot cards, I would be in danger if I turned left.
I notice in some movies, well, some super hero movies, this most profound scene, close to the climax, is very likely to happen. The bad guys messed up the city, chaos everywhere, fire, flood, you-name-it, the super hero's girl would get up and said to the newly found super hero guy, "Come on! Go get them!" And when the super hero guy turned out to be shallow and told the girl that he had lost his power, the same girl would bravely say, "Just believe in yourself. We need you." The guy got up. Believing in himself, he got the super power back from nowhere (something that Rhonda Byrne's The Secret can explain), and walked out as the mighty super hero, someone that we'd known would be even before we bought the movie ticket.
Now let's compare if the movie stopped where "Just believe in yourself" line had ended, would you be a fan of the super hero guy when the credits title appeared?
Me? I want to see the super hero win. I want to be the super hero. I don't want to be just believe. I don't want to regret my life when my credits title of life appear. I don't want to leave such "WHAT IF" questions to them, who cry endlessly and flood my funeral with "she is a good girl. she COULD BE big." I don't want to cry out when my time is over, knowing that I should have been doing something more than just believe.
I want to nail my life. To believe in my ability to do so is just a start.
Just for fun, I believed in my strength to move this small tractor. :p