“It is indeed true that both the planting and watering of the preacher and the activity and desire of the hearer would be in vain, and no conversion would result from these efforts, if the power and action of the Holy Spirit were not added to them. For the Spirit enlightens and converts hearts through the Word that is proclaimed and heard, so that people believe the Word and say yes to it.

“Therefore, neither the preacher nor the hearer should doubt this grace and activity of the Holy Spirit, but they should be certain that when the Word of God is preached purely and clearly according to God’s command and will and people listen to it seriously and diligently and meditate upon it, God will certainly be present with his grace and give, as has been said, what human beings otherwise could neither receive nor take on the basis of their own powers. For the presence, effectiveness, and gift of the Holy Spirit should not and cannot always be assessed ex sensu, as a person feels it in the heart. Instead, because the Holy Spirit’s activity is often hidden under the cover of great weakness, we should be certain, on the basis of and according to the promise, that the Word of God, when preached and heard, is a function and work of the Holy Spirit, through which he is certainly present in our hearts and exercises his powers there.”

– Formula of Concord, SD Art. II (55-56)