1. Full of or characterized by extreme anger; raging.
2. Suggestive of extreme anger in action or appearance; fierce. See Synonyms at angry.
3. Full of activity; energetic or rapid: the furious pace of the trading floor.
I have come to love this song but while thinking about it I was trying to understand why we say God's love is furious, it sounds like He's pretty ticked off or something.
Description 3 in the definition makes perfect sense to me, His love is always moving and being demonstrated toward us, His love is full of energy, never lackadaisical. That makes sense! In my search to better understand why we say God's love is "furious" I found a great sermon