8 So then, my Brethren, have charity. I have explained it to be this garment, this “wedding garment.” Faith is praised, it is plain, it is praised: but what kind of faith this is, the Apostle distinguishes. For certain who boasted of faith, and had not a good conversation, the Apostle James rebukes and says, “You believe there is one God, you do well; the devils also believe and tremble.” Call to mind with me whereupon Peter was praised, whereupon called blessed. Was it because he said, “You are the Christ, the Son of the living God”? He who pronounced Him blessed, regarded not the sound of the words, but the affection of the heart.
For would ye know that Peter's blessedness lay not in these words? The devils also said the same. “We know You who You are, the Son of God.” Peter confessed Him to be “the Son of God;” the devils confessed Him to be “the Son of God.” “Distinguish, my lord, distinguish between the two.” I do make a plain distinction. Peter spoke in love, the devils from fear. And again Peter says, “I am with You, even unto death.” The devils say, “What have we to do with You?” So then you who have come to the feast, glory not of faith only.
Distinguish well the nature of this faith; and then in you is recognised “the wedding garment.” Let the Apostle make the distinction, let him teach us; “neither circumcision avails anything, nor uncircumcision, but faith.” Tell us, what faith? Do not even the devils believe and tremble? I will tell you, he says, and listen, I will now draw the distinction, “But faith which works by love.” What faith, then, and of what kind? “That which works by love.” “Though I have all knowledge,” he says, “and all faith, so that I could remove mountains, and have not charity, I am nothing.”
Have faith with love; for love without faith ye cannot have. This I warn, this I exhort, this in the name of the Lord I teach you, Beloved, that you have faith with love; for you may possibly have faith without love. I do not exhort you to have faith, but love. For you cannot have love without faith; the love I mean of God and your neighbour; whence can it come without faith? How does he love God, who does not believe in God? How does the fool love God, “who says in his heart, there is no God”? Possible it is that you may believe that Christ has come and not love Christ. But it is not possible that you should love Christ, and yet say that Christ has not come.
Source: Sermons on Selected Lessons of the New Testament (New Advent)