Thinking outside the box is problematic because usually the thinker is inside the box (which is why it's called 'Outside the Box thinking'). As American Christians, we've created a box, one that we're struggling to get outside of. We've been infected by the outside. Thus out box, just like Christian's boxes during many parts of church history, has become tainted and less than what it should be. For this reason, the church has failed to live up to it's calling. The church alienates the world, instead of bringing hope to it, when it fails to be true to it's nature.
For this reason, we look for catchy ways to attract people to the church. We try catchy marketing, campaigns, and creative approaches to our presentation in order to accomplish our goal of attracting people. The problem with this form of "thinking outside the box" is that it is really the box we've already created; it's not thinking outside the box at all. Thus we get stuck in a cycle that really is not taking us anywhere.
I believe the root of the American churches problem is that it fails to understand the unity of the who and how of Jesus. The who is right belief of who Jesus is, we call this orthodoxy (simply right belief). The how of Jesus is the context of the Biblical story this leads to orthopraxy (simply right living). Simply there is no division between the two - they are one!
I think we need to get outside the box of only making sure we have orthodox thinking. In this way of thinking, the emphasis is on getting people to believe what you believe. Thus turning orthodoxy (the who) into a product to be marketed (which just makes me cringe, I hope you did too when you read that). As Christians, we cannot do this, it fails to understand the unity between the who and how of Jesus.
How would we change our churches if we focused as much on how we live as what we believe. I think it would make people uncomfortable. We don't like being told what to do. We like being told things that don't affect how we live our lives. Quite often, we're very comfortable with who we are, or we've tried for years to bury what we're uncomfortable with and don't enjoy having to dig that up.
A Christianity that thinks outside the box would be a Christianity that challenges it's believers to live out the Gospel where they are. What would that look like? What would it look like if a congregation lived as one. How different would a church look if it was continually trying to give away it's power & authority instead of trying to gain more. What if a church started to treat their neighbors as more important? What if a church began to question the justice of the rich side of town opening new pools while closing pools on the poor side?
Maybe that would be thinking outside the box...