During my time interning at a campus ministry, I asked one of our engineering students just how loud a sound would have to be to break a cedar tree, as described in verse 5. He said that wasn't his field. But we found out the eruption of the Krakatoa volcano in 1883 was heard as far as 3,000 miles away, which gives an estimate of about 180 deciBels, or more than 10 times as loud as a jet engine from 100 feet away. We figured it would have to be louder than that.
If you were to "hear" a sound that was loud enough to break a cedar tree, it would obviously do you serious damage as well. Probably fatal; we figured it would literally pulverize your bones and probably turn all your body's soft tissue to mush.
And this is how the psalmist describes the voice of God. Now, does he mean it literally? Sometimes, it's best to take the Bible at face value. But the psalms are songs and poetry, which means they have some poetic imagery that's unlikely to be meant literally. After all, in verse 6, God's voice makes nations jump around like calves, and I can't imagine anyone thinking that the whole country of Lebanon jumped around like a calf.
I think the psalmist wants to offer a picture of what the voice of God is like in terms of its power, using that kind of poetic imagery. People who had heard the loud voice of a priest or a military commander would know that some sounds could be powerful, and they would have seen that lightning or maybe powerful winds could take down trees. Well, God's power was so great that merely his voice could cause the same level of destruction as a mighty storm could. Everybody who heard the psalm probably knew that God's power was even greater than that, but it gave an image they could use -- it was power beyond their capability to imagine, let alone duplicate.
The Israelites, of course, were not the only people who claimed their gods had immense power. Remember your Greek mythology, with Zeus and his thunderbolts. But the Israelites did do something a little odd in light of their claims about God's power. After all, if you knew there was a being with power so great and potentially destructive that a simple word could break a mighty tree, what would you do?
I myself would follow a three-step plan: 1) Run; 2) Run fast; 3) Run far. Whatever it took to stay beneath the notice of such a powerful being, I would do. If I had to, I'd offer sacrifices or such when I was required to, but I'd do them and get them over with. I wouldn't do anything to call the attention of such a being unless I had to. I might respect such force, but chances are pretty good I'd mostly be afraid.
What do the Israelites do, though? Well, read their psalms and their prayers -- they call upon the name of their all-powerful God. They don't run or hide, they regularly call for their God to be present with them -- for that incredible destructive power to be right there with them! More than that, they "enter his courts with praise!" They are glad when someone says, "let us go to the house of the Lord!" They even claim to be in a covenant with their God, not one of fear, but of promise!
And there's the key: The Israelites respect God's power but they're not afraid of it, because their God has promised them he is on their side. That power will not be used against them, but to protect them and build them up. God has promised them this.
We Christians claim that in Jesus, the fullness of God came to dwell in human form, including the same awesome power that the psalmist describes in Psalm 29. And Jesus lived out the same promise of God; that this mind-blowing power would be used not to terrorize or intimidate but to build up and lift up. Though Jesus could claim for himself the limitless abilities of God, he chose to identify with us and our human limitations.
That's one message of his baptism. The fullness of God is on our side, so much so that Jesus will not stand on it and take a pass on the symbolic cleansing of baptism but will instead participate in it along with us.
Sometimes when we baptize someone in the church, we include some words to those who are there supporting the person being baptized: "Remember your baptism, and be thankful." We can do that because we are remembering our baptism, remembering that Christ himself shared that baptism with us, and remembering that the magnificent power of God is not against us, but for us.
And that sounds like good news to me.