Even the demons know God, and shudder. In a sense, because the Lord is Almighty Sovereign, even the demons obey him. Faith they do not have, and thus cannot receive salvation.
But we who are saved, what is Faith to us? Faith is the assurance of things hoped for, and conviction of things unseen. Faith is worked in our hearts by the Father’s immeasurable grace in kindness toward us according to his love for His Son, whose we are.
But on this physical plane of consciousness, our faith is a work of love. Our love for the Father (as Christ in us) produces faith. How can you trust someone whom you hate? How can you hold fast to a branch you do not know?
As the Apostle says, “So now faith, hope, and love abide, these three; but the greatest of these is love.”