Light a Fire is a theme created to represent the fire of God in our life. It is an invitation for God to let His fire burn away the impurities of our heart and life so we can be more like him.
Zechariah 13:9 say:
This third I will put into the fire; I will refine them like silver and test them like gold. They will call on my name and I will answer them; I will say, 'They are my people,' and they will say, 'The Lord is our God.'"