I wrote this in response to a question on a Christian forum about what sorts of LEGO God would want us to build. That discussion went down a lot of unhelpful rabbit trails, starting with some argument about whether Star Wars (the Force) and Harry Potter (witchcraft) were evil, but I was intrigued by the initial question. Some people responded with thoughts of "LEGO is just a toy - it doesn't matter - God doesn't care - why would someone even raise the question?" I thought a little differently and wrote the thoughts below. Remember, this was written in a specifically Christian setting to a (presumably) Christian audience, so certain assumptions come along with that discussion. I'd be interested in hearing others' thoughts (and please, no running down rabbit trails about the Force and witchcraft and ending up in a completely unrelated argument about creationism or the sexual scandals involving Catholic priests) (that's what the aforementioned discussion ended up as, BTW).
In thinking about what a Christian should, or should not, do with LEGO, I start with the assumption that LEGO is (or at least can be) a form of art. It seems obvious that some art can be done to the glory of God - think of the ceiling of the Sistine Chapel, or the great Gothic cathedrals, or Handel's Messiah. These are all explicitly pointing to God. I think we can go beyond specifically religious subject matter, though. In discussing what it means to be a Christian author, Madeline L'Engle writes "to paint a picture or to write a story or to compose a song is an incarnational activity."1 Tolkien writes that the role of an author (and, we can assume, other artists (especially since he expands the metaphor to a painter in "Leaf by Niggle")) is to act as a sub-creator.2 The artist can be "inspired", that is, follow the leading of the Spirit, in a way that adds to creation and lifts the human condition. In addition to art that is sacred, it also seems obvious that some art can be profane. Some artists specifically set out to offend religious sensibilities (think, for instance, of the artist who put a crucifix in a jar of urine). An idol is another instance of profane art. I'd go further to say that any art that sets out to degrade people could also fall in this category (people being made in God's image). What is more questionable, perhaps, is if there is art that is neutral—neither sacred nor profane. We are told to do all things to the glory of God (e.g. 1 Cor 10:31), but some actions seem pretty neutral. For instance, I just scratched the tip of my nose while writing this. I cannot see what import that action has one way or the other. The same can be said of much art. I'm not sure what we could say one way or the other about a still life of a bowl of fruit, for instance.
Turning back to LEGO, I think most things that people build fall into this third, neutral category, whether it be a spaceship, a castle, or a train. So I really wouldn't worry from a negative standpoint about what you're building being offensive to God. Perhaps we should put more thought, though, in the other direction. "All things are lawful, but not all things edify." (1 Cor 10, again) If the central fact of our existence is our love for God, how is that reflected in our hobby? By this I don't just mean we should be building little crosses out of LEGO or illustrations of Bible stories, but are we following the leading of the Spirit in what we do? Is there a way that my most recent MOC can somehow add beauty to creation or lift up our eyes to something higher? It is, I suppose, a twist on the WWJD idea - what would Jesus build? It's probably a good challenge to us all.
Just to add a quick note from a different perspective, this blog post encourages Muslim parents to "Play like the Prophet" - that is, to encourage their children to play in ways that Muhammad would as part of making their faith real to them. They specifically note running, swimming and wrestling, as I gather there are references to Muhammad doing those things during his life. Muslim LEGO builders may ask themselves how their building might reflect their beliefs. For instance, I might assume that they would be less likely to do representations of people.
1From Madeline L'Engle Walking on Water: Reflections on Faith and Art - the whole book is an extended essay in response to a question she got from a student about what it means to be a Christian author.
2He develops this idea in various places (e.g. in his letters), but it is easiest to find in the essay "On Fairy-Stories," originally in Essays Presented to Charles Williams, but reprinted in both Tree and Leaf and The Tolkien Reader, which may be easier to find.