Here's my translation of "You can't put God in a box!" What they mean is, "You can't put God into your box, because he can only fit into mine!" Or, "You can't really know about God! I already know what God is like [tongue in cheek!], so don't confuse me with the facts!"
Why not simply be honest and say, "I like my boxes better than your boxes. Please leave my boxes alone!" Better yet, why not say, "Yes, let's compare our theological boxes, examine them carefully and honestly, and learn to build better boxes (keeping in mind our limitations)."
(Hello? Is anybody still reading?)
Of course, by speaking of theological boxes, I do not mean that we can contain God with our theology. But in order to have thoughts about God at all, our ideas must necessarily have boundaries (unless you are a theological voluntarist!). Consider, for instance, John's statement: "God is light, and in him is no darkness at all" (1 John 1:5). Now that's a good box!
I think I understand why people use this saying, and I have probably used it myself. We too often live with a stunted faith and our small actions reflect our small theology. It is a wholly appropriate way of challenging ourselves and others to a bolder faith and larger living. But it is a wholly inappropriate way of dismissing theological proposals we do not like, or worse, attempting to demolish the task of theology altogether because we think it is too hard.
The fact of the matter is, we all have theological boxes. That is a given. And we should just relax...it's nothing to be ashamed of...really! What is important is that we have boxes that are adequate to accommodate the kind of faith God has called us to live. What is really important is that we have boxes that will grow with us as we grow in Christ. Remember Lucy's conversation with Aslan?
"That is because you are older, little one," answered he.
"Not because you are?"
"I am not. But every year you grow, you will find me bigger." (Prince Caspian)
Every year you live, may you find him bigger.