I wrote here asking the question: Would you invite Jesus Christ to your birthday party? The question reveals some of our gut-level impressions of who we think he is, and what he’s like.

Tim Keller observed that our attitudes toward following Jesus can be very revealing to how we think of him. On the one hand we default to a slavish, duty-oriented service. Far better, is what Keller calls “the perennial note of surprise.” Is Christ a grumpy boss? Or a friend who rescues?

We should be just as shocked that God would give us–with all our smallness and flaws–such a mighty gift. And so no Christian should be far from this astonishment that “I, I of all people, should be loved and embraced by his grace!”

I would go so far as to say that this perennial note of surprise is a mark of anyone who understands the essence of the Gospel. What is Christianity? If you think Christianity is mainly going to church, believing a certain creed, and living a certain kind of life, then there will be no note of wonder and surprise about the fact that you are a believer. If someone asks you, “Are you a Christian?” You will say, “Of course I am! It’s hard work but I’m doing it. Why do you ask?” Christianity is, in this view, something done by you–and so there’s no astonishment about being a Christian. However, if Christianity is something done for you, and to you, and in you, then there is a constant note of surprise and wonder….So if someone asks you if you are a Christian, you should not say, “Of course!” There should be no ‘of course-ness’ about it. It would be more appropriate to say, “Yes, I am, and that’s a miracle. Me! A Christian! Who would have ever thought it? Yet he did it, and I am his.”

Timothy Keller, Hidden Christmas, 89.