The answer is given by the Fathers of the Church, to whom we always turn and in whom we find the answer, regardless of when they lived.
St. Simeon of Thessalonica speaks of six things which the candle symbolizes, referring to the pure candle, viz. – the waxy one. He says she depicts:
1) the purity of our soul,
2) the flexibility of our soul, which we must shape according to the evangelical commandments,
3) the fragrance of God’s Grace, which should emanate from every soul, like the sweet smell of a candle,
4) as when the real wax in the candle mixes with the fire, burns and nourishes it, so the soul, burned by God’s love, gradually reaches deification,
5) Christ’s light,
6) the love and peace that reign in the Christian and become a signpost for others.
St. Nicodemus of Athos also talks about six symbols and reasons why we light candles:
1) to glorify God who is Light: “I am the Light of the world” (John, 8:12),
2) to dispel the darkness of the night and drive away the fear it brings,
3) to express the inner joy of our soul,
4) to honor our saints, imitating the ancient Christians who lit candles on the graves of the martyrs,
5) to depict our good deeds according to Christ’s words “let your light shine before men” (Matt. 5:16a),
6) to forgive the sins of those who light the candles and of those for whom they are lit.
A flame comes out of the candle and the flame emits light. Light is the main element in our services. We are called to become light as He is Light. During the pre-sanctified Holy Liturgy, the officiating priest turns to the faithful with a lighted candle in his hand and says: “The light of Christ enlightens everyone.” During the monastic haircut, the abbot holds a lighted candle and says again “Let your light shine before men, so that they may see your good deeds and glorify your Heavenly Father.” (Mat 5:16), but also at the end of the Holy Liturgy we sing “having seen the true light”. Our Lord constantly calls us to become Light with our lives, with our words and deeds. This means that lighting candles should not be just some routine or mechanical action, but should become an important part of our search for God and our communication with Him.
Photo by Zenia: https://www.pexels.com/photo/lighted-candles-11533/