Summary: Humanity is at the same time insignificant and the pinnacle of God’s work of creation
The danger with a series of sermons on the theology of humanity, the danger of thinking about who we are, what we’re here for, what it means to be human, is that it could, very easily, turn into just another exercise in humanism. We could spend our time thinking about all the great things human beings have achieved over the years, the great advances we’ve made, the improvements to quality of life, to health and education. On the other hand, I’m sure that’s prompted some of you to think about the negatives of human development: of the damage we’ve done to the environment, of the pain and suffering we continue to inflict on one another, of the way humans misuse power, give in to corruption, allow injustice to go unpunished. But if we take that tack, of concentrating entirely on humanity, we miss the bigger picture and make humanity the centre of the universe.
David doesn’t make that mistake. He begins and ends this psalm with praise of God, who made the heavens and the earth and everything in them. Even though the majority of the psalm is taken up with a discussion of humanity, it’s clearly God who’s central. It’s God who has made us what we are. It’s God whose image we reflect in the glory we show forth in our lives.
You can imagine David sitting out on the hills at night, under a clear sky, looking up at the heavens and being overwhelmed. Blown away by the wonder of the heavens, and then as so often happens in that sort of situation, beginning to think about his own mortality.
He looks up and bursts out in praise: "O lord, our king, how majestic is your name in all the earth!" In Psalm 19 (quickview)  we find a similar idea: "The heavens are telling the glory of God; and the firmament proclaims his handiwork. 2Day to day pours forth speech, and night to night declares knowledge." It’s as though the inanimate world has a voice that continually sings God’s praises. Jesus said a similar thing to the Pharisees on the first Palm Sunday, "I tell you, if [my disciples] were silent, the stones would shout out." God is so great that even the inanimate stars and planets proclaim God’s glory.
But then at the other extreme, "Out of the mouths of babes and infants you have founded a bulwark [that is, a defence] because of your foes, to silence the enemy and the avenger." If the universe declares the glory of God, so too do babes and infants.
I wonder if you remember the first time you were taken out of the city, to camp out in the bush, under the stars? Do you remember the awe and wonder as you looked up at the milky way. Do you remember being amazed at their brightness, a brightness you never see in the city, at their number, beyond counting, at the vast expanse of them, covering the sky. Young children, in their innocence, can often sense what we sophisticated adults are blind to. It might be possible for an adult to look up at the stars in a blasé way as though there were nothing new there. But a young child will be blown away by the same sense of wonder as David expresses here. And it’s that innocent acknowledgement of God’s glory that defeats the hardness of the sophisticated. In fact the weakness and gentleness of infants is often the chosen defence of God against the powerful and violent. Listen to how Jesus takes the words of this psalm in Matt 21:15 (quickview) , to answer the Pharisees’ objections: "When the chief priests and the scribes saw the amazing things that he did, and heard the children crying out in the temple, "Hosanna to the Son of David," they became angry 16and said to him, "Do you hear what these are saying?" Jesus said to them, "Yes; have you never read, ’Out of the mouths of infants and nursing babies you have prepared praise for yourself’?"