In ancient times candles were used in the church for a very practical reason: to provide light. Adequate lighting was especially important in churches, where the officiants of the liturgy relied on liturgical books to conduct the lengthy worship services. Apart from this strictly functional use, burning candles remind Christians of one of the most common and evocative metaphors for God in the Bible. Jesus says, “I am the light of the world; he who follows me will not walk in darkness, but will have the light of life” [John 8:12, 9:5].
Until the relatively recent age of electricity the only source of light besides the sun came from the flame of the candle. Our ancestors were aware of the awesome power of fire, both to create light and heat, but also to burn and destroy. Church candles therefore evoked for them not only Christ the light, but Christ the Judge, who is “ordained by God to be judge of the living and the dead” [Acts 10:42] and to cast them into the flames of hell [Luke 12:5], Earlier generations may have perceived this more acutely than we do today. Still, when Armenian Christians light candles as they offer their personal prayers in church, many are drawn closer to our loving and compassionate God as they gaze at the light of the flame and feel its warmth.
Source: Frequently Asked Questions on the Badarak, The Divine Liturgy of the Armenian Church by Michael Daniel Findikyan.