Quotes from St. Seraphim of Sarov on the fire of God:
"God is a fire that warms and kindles the heart and inward parts. And so, if we feel in our hearts coldness, which is from the devil—for the devil is cold—then let us call upon the Lord, and He will come and warm our hearts with perfect love not only for Him, but for our neighbor as well. And from the presence of warmth the coldness of the hater of good will be driven away."
"God is a fire that warms and kindles the heart and inward parts. And so, if we feel in our hearts coldness, which is from the devil—for the devil is cold—then let us call upon the Lord, and He will come and warm our hearts with perfect love not only for Him, but for our neighbor as well. And from the presence of warmth the coldness of the hater of good will be driven away."