It is commonly said among Lutherans that we should not look to ourselves and our life to see whether we are Christians. Rather, we direct people to the external Word and teach them to say, “Nevertheless, I am baptized!” This is true for the troubled and terrified conscience. The healthy conscience, however, should also see evidence of the fruits of faith in one’s life. The seared conscience should especially be directed to its false works so that it may be encouraged to stop deceiving itself and return to faith and baptism. In such a case Luther himself has no qualms about directing people to look to their works as a sign of true faith.
This is what St. James means when he says: “Faith which does not work is dead. Just as the body without the soul is dead, so faith without works is also dead” (James 2 [:17, 26]). This does not mean that faith is in a person and does not work, which is impossible, for faith is a living, restless thing. Rather, this means that people should not deceive themselves and think they have faith when they have none of it; rather, they should look at their works, that is, whether they also love their neighbors and do good to them. If they do this, it is a sign that they have the true faith (AE 79:76).
After all, faith and its fruits are inseparable:
Thus it is impossible to separate works from faith, quite as impossible as to separate heat and light from fire (AE 35:371).
Thus we have it that faith justifies without any works; and yet it does not follow that men are therefore to do no good works, but rather that the genuine works will not be lacking (AE 35:374).
The Apology says reiterates Luther’s scriptural teaching, daring even to place the good works of the Christian alongside the signs of Baptism and the Lord’s Supper:
“Christ often connects the promise of the forgiveness of sins to good works” (1) to warn against hypocritical faith (2) our good works serve as a sign of the promise to strengthen faith as does Baptism and LS (Ap. III, De dilect. et impl. legis, 154-155).
For why shouldn’t my faith be strengthened by the good works of others, and even by my own when I consider what great things the Lord has done in my life (Philem. 7; 2 Cor. 9:11).