This from Hebrews 12:
You have not come to a mountain that can be touched and that is burning with fire; to darkness, gloom and storm; 19to a trumpet blast or to such a voice speaking words that those who heard it begged that no further word be spoken to them, 20because they could not bear what was commanded: "If even an animal touches the mountain, it must be stoned." 21The sight was so terrifying that Moses said, "I am trembling with fear."
22But you have come to Mount Zion, to the heavenly Jerusalem, the city of the living God. You have come to thousands upon thousands of angels in joyful assembly, 23to the church of the firstborn, whose names are written in heaven. You have come to God, the judge of all men, to the spirits of righteous men made perfect, 24to Jesus the mediator of a new covenant, and to the sprinkled blood that speaks a better word than the blood of Abel.
25See to it that you do not refuse him who speaks. If they did not escape when they refused him who warned them on earth, how much less will we, if we turn away from him who warns us from heaven? 26At that time his voice shook the earth, but now he has promised, "Once more I will shake not only the earth but also the heavens." 27The words "once more" indicate the removing of what can be shaken—that is, created things—so that what cannot be shaken may remain.
28Therefore, since we are receiving a kingdom that cannot be shaken, let us be thankful, and so worship God acceptably with reverence and awe, 29for our "God is a consuming fire." [NIV, emphasis added]
I find this passage profound, because the writer places fear of God in a new context. First, he explains old way: God storms at the people from the mountain. In the old covenant, when God was near he was also very distant. The people trembled when God came near. He spoke from the storm and with fury.
This old way is in contrast to the new covenant: angelic glory, joyful assembly, redemption through Christ's blood. The comparison yields the conclusion: there is something better in the new way.
But the new way of joy and redemption begs the question of what place the fear of God may have. For the writer, the answer seems obvious: in light of what you are receiving, worship appropriately, namely, with reverence and awe. He then suggests the consistency between the old and new way: our God is a consuming fire.
The book of Hebrews is fascinating, because the author is reworking the entire Old Testament into a new framework. Sometimes the old fits well in the new; at other times the old needs to be radically recontextualized. In Hebrews 12, the constant is the God of a consuming fire; but the context is new. It is a unique Christological context. So, even the God of consuming fire is recontextualized.
Personally, I deeply appreciate the grace and joy of the Christian life; it is something I am only beginning to realize, I think. I try to start over with each new day: today I am a new Christian who is just now experiencing God's grace for the first time.
Yet as much as I love walking in God's grace, I also appreciate the moments when I can tremble in God's presence. Both God's grace and his consuming fire relate to his presence and nearness. God remains mysteriously non-disposable. In other words, there is no formula to conjur up his presence. He just appears. Or disappears. I don't mean to suggest that we should not seek him, but only that God is often like Lewis's Aslan in that he so often refuses to be compartmentalized or used. He resists the economics of market exchange where we can pay a price for a product that we consume for our own use. Nay, in fact, if there is an economics at work, then the reverse seems to be the case: it is God who is the consumer, the consuming fire. In many ways, it is we who are at his disposal.