In my hometown there were 3 churches: the Lutheran church, the Catholic church, the Methodist church, and oh yeah the Holy Rollers. So if someone asked "What are you?" in reference to your beliefs you were identified by what church you went to. I was a Lutheran.
And I was just thinking, if someone had asked me, back then, "Are you a Christian?", I think my knee-jerk answer would have been to say, "No, I'm a Lutheran." And that just struck me as funny. Both funny ha-ha and funny interesting.
It might be that the connotation of being a "Christian" was more fundy/bible thumper- one of those born-again types. My dad took special exception to people being born-again. He figured he was baptised, confirmed, took communion, went to church on Sunday, he was golden.
Anyway, I hadn't really thought much about it until just know.