I hear a lot of people say that, but I have to wonder if it is entirely accurate, given the nature of the 1st Commandment.
Did 'polite society' really expect non-Christians to hide their faith?
Based upon my conversations with my grandparents, it wasn't really an issue. Religion just wasn't discussed in public. It wasn't like Christians back then were going about in public being obnoxiously Christian; their behavior was just the result of their faith.