Fire, in the spiritual sense, can mean either love or hatred depending on the context, just as natural fire can be either comforting in keeping you warm, or scary in burning down your house. Our language reflects this, too -- we use concepts like a smoldering hatred or a burning love. So fire signifies a love, either a good love of the neighbor and to the Lord, or, in a bad sense, selfish love of oneself that, if unchecked by conscience, leads to hatred of anyone that opposes it.

93. Those who are spiritually adulterous are distinguished from those who are naturally adulterous. The latter, if they have taken pleasure in adulteries and no pleasure in marriages are shut out of heaven and are sent to hells. But the spiritually adulterous, although they feel there is nothing in adulteries which is not allowed, are all the same examined, and some are reformed; others are given places in accordance with their lives.