Jesus said that he was the Light of the World and that He came to shine a light for a dark and sin-filled world. His Light was Truth exposing the sin that hid in the blackness.
Catholics light candles during official church services (called liturgy, such as the Mass) to indicate the special solemnity of the occasion.
Catholics light votive candles or “vigil lights” to pray about something particular, either for themselves or on behalf of someone else. When we light a candle with a prayer intention, we are not only praying, but also our prayers actually become smaller symbols of the One Light of Christ. When we burn prayer candles, our prayers rise up to Heaven day and night.
Early Christians associated light with the sacred presence of Our Lord in their midst, assured by Him: “Wherever two or three are gathered in my name, I shall be in their midst” (Mt.8:20). Thus, during their evening gatherings, as the candles or lamps were being lit, the Christians symbolically (mystically) welcomed the Eternal Light, Jesus, into their midst.
When we light our prayer candles, we remember and truly live the words of Our Lord to become light in the darkness.