Faith assures us of things we expect and convinces us of the existence of things we cannot see.
God accepted our ancestors because of their faith.
Faith convinces us that God created the world through his word. This means what can be seen was made by something that could not be seen.
Faith led Abel to offer God a better sacrifice than Cain's sacrifice. Through his faith Abel received God's approval, since God accepted his sacrifices. Through his faith Abel still speaks, even though he is dead.
Faith enabled Enoch to be taken instead of dying. No one could find him, because God had taken him. Scripture states that before Enoch was taken, God was pleased with him.
No one can please God without faith. Whoever goes to God must believe that God exists and that he rewards those who seek him.