Such are those who have renounced self-justification and have embraced the righteousness of Christ which the gospel offers. But at the same time, they do not yet see clearly all that Christ offers. When such a person begins to doubt, let him counteract such a temptation in the following ways.

In the first place, let one who doubts regard this temptation as evidence of his progress in the Christian life. Let him recognize that had he not wished a desire to believe, he would not be so tempted to doubt. His very distress is indicative of the presence of the Holy Spirit in his life.

In the second place, let him argue like this: If this Christian faith that I have were not something spiritual and divine, it would not find me the contradiction that it does find. Let this comfort me.

In the third place, let him also argue thusly: If this Christian faith were not the gift of God, I would not feel such inward new desires to be united with Christ. But these are the very desires I have since embracing Him in faith.

In the fourth place, let him also think like this: If a Christian’s faith was not spiritual and divine, it would not give rise to that very tension I experience between faith and doubt.

Finally, let him think like this: If I knew of any alternative that is better than this, or even equal to this, in getting me to appear before the judgment of God, I might have good cause to doubt the truth to which I know cling. But since I see no alternative that is better or equal to it, I have no cause to doubt.

–Juan de Valdes, the Italian Reformer from Naples (1498-1541), in his The Benefit of Christ.