True beliefs are the things that you do, not the things that you say (unless they are both the same). For example, a person can say, " I believe that you can carry a man on your back as you walk across Niagra falls on a tight rope." But then that person is asked, "Will you be the person who is carried on the tightrope walker's back?"
True belief is more than just a mental assent (i.e. "I believe that ...."). True belief will actually do it. For example, if you say that you believe in God, but you don't live in accordance with God's commandments and ...., I would question when you truly believe in God. Your actions are what show your true belief.