Christianity is not a unified body of doctrine, and a very plausible explanation for why people typically “act as though some things about Christianity are true but not others” is that they in fact believe that some things are true but not others.
That’s the inverse of “no true Scotsman”. “No true Scotsman” refers to the situation where you arbitrarily exclude people who you don’t want to count as members of a class, by saying “that isn’t really Christian”. In this case, you can arbitrarily include people who you do want to count, by saying that any non-Christian things about them aren’t really non-Christian.
Then every Christian can count as a religious Christian.
Christianity is not a unified body of doctrine, and a very plausible explanation for why people typically “act as though some things about Christianity are true but not others” is that they in fact believe that some things are true but not others.
That’s the inverse of “no true Scotsman”. “No true Scotsman” refers to the situation where you arbitrarily exclude people who you don’t want to count as members of a class, by saying “that isn’t really Christian”. In this case, you can arbitrarily include people who you do want to count, by saying that any non-Christian things about them aren’t really non-Christian.
Then every Christian can count as a religious Christian.