Faith is an unwavering belief in the power of God, it is the act of believing that God is able to perform impossibly miraculous feats and acknowledging such feats to have been accomplished, even when such feats are yet to be made manifest, because you know in your heart that there is nothing too difficult for God.

Heb 11v 1 states "faith is the substance of things hoped for and the evidence of things not seen". And every christain needs it because without faith it is impossible to please God.Heb 11v6