Set up the lamp on the lampstand
Our Lord called his disciples “the light of the world” (Mt 5:14) because they have been enlightened by the one who is the true and eternal light (Jn 1:9) and so themselves have become light in the darkness. Since he is himself “the Sun of justice” (Mal 3:20), it is not without reason that he also calls his disciples “the light of the world”. He has spread the light of his knowledge throughout the world through them as through rays of light… We, too, have been enlightened by them, and from being darkness we have become light, as the apostle Paul says: “For once you were darkness but now you are light in the Lord: walk as children of light” (Eph 3:8). And again: “You are not sons of night nor of darkness but you are sons of light and of the day” (1Thes 5:5). And in his epistle Saint John rightly states: “God is light” (1:5) and “whoever remains in God is in the light” (1:7)…Because we have the good fortune to be freed form the darkness of error, we should always walk in the light like sons of the light. And so the apostle Paul says: “Among them you shine as lights in the world, holding fast the word of life” (Phil 2:15)…
Therefore that shining lamp that has been lit for our salvation must always shine in us… We must not hide this lamp of the Law and of faith but should always set it up in the Church as on a lampstand for the salvation of many. In this way we, too, may enjoy the light of truth itself and all who believe may be enlightened.
St. Alphonsus Maria de Liguori