If the "cross in the dirt" story were true, wouldn't a good Christian have "witnessed" to it early on?

In this Bloggingheads clip, Bob Wright and I refer to different aspects of Christianity (and talk about this Andrew Sullivan post). (At the end, I ask who's more religious, McCain or Obama, and propose a bet that might shock you.)



Watching this now and comparing Bob's take on Christianity to mine, I have a theory about why McCain shifted from not talking about the cross to talking about it.

McCain was initially an Episcopalian, and only fairly recently identified himself as a Baptist. My Christian upbringing was Episcopalian, and Bob Wright was raised as a Southern Baptist. Bob thought of Christianity as something to witness at every opportunity, and I thought Jesus's admonition to keep one's religion private (which comes in Matthew 6, just before he gives the words for the Lord's Prayer):

Beware of practicing your righteousness before other people in order to be seen by them, for then you will have no reward from your Father who is in heaven.

Thus, when you give to the needy, sound no trumpet before you, as the hypocrites do in the synagogues and in the streets, that they may be praised by others. Truly, I say to you, they have received their reward. But when you give to the needy, do not let your left hand know what your right hand is doing, so that your giving may be in secret. And your Father who sees in secret will reward you.

And when you pray, you must not be like the hypocrites. For they love to stand and pray in the synagogues and at the street corners, that they may be seen by others. Truly, I say to you, they have received their reward. But when you pray, go into your room and shut the door and pray to your Father who is in secret. And your Father who sees in secret will reward you.

Could it be that McCain, as an Episcopalian, thought more like I did, and then later, after becoming a Baptist, saw the matter more the way Bob did?

ADDED: I tweak the eminently tweakable Episcopalians: