The Mezzanine

I think one of the things that resonates with me about this is that things like sacrifice, duty, redemption, guilt, love, failure, and family aren't so much "Christian" things or "non-Christian" things. They're human things - we all live with them, whether or not we follow a particular religious faith. All of us have to deal with them, at various levels, and all of us can use some examples of how to deal with them.

This is why "an avowed atheist" can write stories about these things which are capable of speaking to even the most reluctant Christian. These themes aren't the exclusive property of Christianity. They're part of the common human experience. When a religion attempts to lay exclusive claim to some portions of the human experience (such as morality, for example) then everyone loses. People inside the religion lose because they're being used as pawns in a power game. People outside the religion lose because part of their essential humanity is being denied and they're being judged as "less than".

Commercialised Christianity, as the OP points out, trivialises all of these. It makes them into selling points for some tacky object or other. In doing this, something is lost, and I think the thing which is lost is the real impact of these themes on everyday life. Commercialised Christianity offers easy reassurance to people who don't want to have to think about any of these topics, and how difficult they actually are. Instead of saying (as Christ did) "yes, this is hard, and it's MEANT to be hard", CC says "buy $PRODUCT_NAME and all your problems are solved". It caters to a style of non-thinking which revolves around fetishising religion, and tokenising it, and making it into something you own or wear as a way of saying "I am a Real Human Being, not like Them".