The image of God's boiling rage inspires the author to focus on the kettle, as you do!
As with other domestic items, he notes the twin aspects of the technology that allows us to boil water, and how it can be employed for in different ways, some good, some bad, some neutral... steam to sterilise, hot water to make tea or coffee and so on.
His summary is that 'love and judgement go hand in hand' - the God who forgives is also the God who smites, and the two are inter-related. Hmm (not a Holy Spirit hmm, just a human hmm I think). The correlation of judgement with smiting/punishing is problematic for me, not because choices don't have consequences, they do, but because bad things happen to good people, and we need to be very wary of seeing cause-and-effect where none such exists. The child who is murdered by an angry or vengeful ex-lover has nothing to do with justice and everything to do with wrath... and somehow the God who is also love has seemingly done nothing. The revered and saintly person whose life is lived for others struck down by a life-threatening illness has nothing to do with smiting or loving, it just is.
Yes, I believe that God is capable of anger, even of rage... but I also believe that God's mercy and love are stronger. If God is a kettle, then it's a huge, automatic kettle, with a very efficient cut-out controller designed to nuclear standards...
The author notes, and disagrees with, the discomfort many (myself included) have with a modern hymn (and otherwise I like it) that says 'on the cross as Jesus died, the wrath of God was satisfied...'
I think the author is wrong... an angry God (wrath) who needs a victim (satisfaction) is no God at all! Let's follow the logic... If Jesus is (only) the son of God, then the cross, killing one human being, is sadistic. If Jesus is (only) God, then the cross is masochistic. If Jesus is both, then this is sadomasochism in extremis, and frankly I just don't get it!
The cross is a profound mystery, an event, a moment when somehow or other God chosen to draw all the pain and suffering caused by human sin and finitude into God's very self. This was no act of wrath, it was an an act of love.
If God is to be compared to a kettle, boiling water, then my prayer is that the water so boiled is employed to make the finest, most refreshing tea/coffee ever!
God of love and judgement, I am sure you do sometimes get very angry about how things are - but I also believe that anger does not lead to retribution, smiting and destruction. Help me to distinguish between sin and those who sin, and to love others as you love me. Amen.