Nothing else deserves this name. If God were merely transcendent, it would indeed be presumptuous to claim any knowledge of God. But a transcendence worthy of God must be so transcendent that it transcends our logical limits of transcendence and is, therefore, perfectly compatible with God's immanence. The fact that I am not simply God needs little proof. To have faith does not primarily mean believing something, but rather believing in someone.
Faith is trust.
It takes courage to trust. The opposite of faith is not disbelief, but distrust, fear. Fear makes us cling to anything within reach. Fear clings even to beliefs. Thus beliefs can even get in the way of faith.