We mustn't understand art simply as expression. This is how it becomes instrumental or utilitarian. Indeed, expression, it seems to me, is too restrictive and inappropriate a category to ground art from a Christian standpoint. Not to mention, too whimsical a characteristic to ascribe to art in general. Creation is too real and too "unreal" for simple expression. That is to say, there is something already before us, and something awaiting us that requires more than an utterance on our part.
I have heard it said that all making is doing, but not all doing is making. Expression is an act of doing, but I wouldn't be so quick to conclude that it is an act of making. Art, it seems to me, at least from from a Christian standpoint, is better understood on the grounds of making than expressing. Particularly, I think it better understood as meaning-making than simply doing. While slight, there is a difference here.
God does not call us to express ourselves. Yet he does call us to make meaning (Genesis 2:19). We are called to give meaning to this world that he has created for us and to nurture and govern it (Genesis 1:28). Art should be understood within this framework. It is giving meaning to this world. In and through art we make things—everything from songs to plays to kitchens—that give meaning to the material goods God has created and given to us to cultivate. Imaging God consists of being obedient in giving meaning to this world.
That said, we must take seriously the fact our meanings are ours and assume responsibility for them. God has given us principles and laws to govern how we make meaning, but it is we who are called to make these meanings. Thus, our works of art are not imitations, but creations.
There is a beautiful irony to be seen here. The things we create or cultivate give meaning to others but also give meaning to us. As we constitute them, they constitute us. They make us reconsider ourselves. Our art affects our artistry. God works through us for others, and works through others for us. Similarly, he works through us to make works and works through our works to work on us. He has given us the materials to work with, and in delight and trust, encourages us to build a playground. But the playground we create in turn "creates" us.
Art, grounded in the law and creational mandate, is accordingly grounded in the gospel and great commission. Art is not a superadditum to our playground. It's not a decoration. It's not icing on a cake. It cannot be understood as a tool, an artifact of a hobby, or a decoration put on the gospel or incorporated into God's Kingdom. It is essential to it. As an artist, God calls forth art from citizens of his kingdom, and their art, like his, make his kingdom precisely what it is. And through their art, artists testify to God's kingdom and give meaning to it for others.
Aristotle said that what convinces is the possible. I like that. I think it testifies to our experience of art. Art places before us a perspective of the possible. It offers us a possible that makes the impossible a reality. Not simply a possible in the future, but a possible in the present. It affords us a possible way of conceiving, interpreting, or hoping right here and right now. As such, art convinces us of the reality of the kingdom. In tangible, incarnational, stimulating, and hopeful ways, art works us in and through the sidewalks of God's kingdom. It mediates and manifests the very kingdom of which it is part and parcel.
And that is why art and the artist are essential to God's kingdom.