What is faith, considered as one of the gifts of the Holy Spirit (1 Cor. 12:9)?

Faith is one of the most valuable of the gifts of the Spirit; granted to all and yet at the same time, a rare gift, disdained by those who arrogantly rely on human ability. The apostle Paul speaks of the faith that moves heaven and the earth, by which the mountains can be moved (1 Cor. 13:2), and some believe that faith is the miracle of drawing hearts to accept Christ’s work of salvation.

St. Cyril of Jerusalem says, “This faith then which is given by grace from the Spirit is not merely doctrinal, but also works things above man’s power. For whosoever has this faith, shall say to this mountain, Remove hence to yonder place, and it shall remove (Mark 11:23) … And of this faith it is said, If you have faith as a grain of mustard seed (Matt. 17:20). For just as the grain of mustard seed is small in size, but fiery in its operation, and though sown in a small space has a circle of great branches, and when grown up is able even to shelter the fowls (Matt. 13:32); so, likewise, faith in the swiftest moment works the greatest effects in the soul.”⁸³⁸