Faith is more than believing, God doesn't call people to believe he calls them to have faith. Faith is like this parable:
You are at the Grand Canyon and there is a man on a tightrope walking back and forth hundreds of feet in the air on a tiny wire. It may seem unbelievable at first, but you watch and he goes across once,twice, even a dozen times and more, to the point where you know that he won't fall and you believe that he can walk across as many times as he wants. However this isn't faith, this is belief. Faith is when that man says to you," Get on my back, and let me carry you across with me" and you say yes, trusting your life with him, and going across.