True belief in Christ is the unreserved trust of a heart convinced of sin—in Christ, as an all-sufficient Savior. It is the combined act of the entire person’s mind, conscience, heart, and will.
It is often so weak and feeble at first, that they who have it, cannot be persuaded that they have it. And yet, like life in the newborn infant, their belief may be real, genuine, saving, and true. The moment that the conscience is convinced of sin, and the head sees Christ to be the only One who can save, and the heart and will lay hold on the hand that Christ holds out—that moment there is saving faith. In that moment a person truly believes.
It is often so weak and feeble at first, that they who have it, cannot be persuaded that they have it. And yet, like life in the newborn infant, their belief may be real, genuine, saving, and true. The moment that the conscience is convinced of sin, and the head sees Christ to be the only One who can save, and the heart and will lay hold on the hand that Christ holds out—that moment there is saving faith. In that moment a person truly believes.
~ J.C. Ryle
Tract: Do You Believe?