This is a slogan that is occasionally used by evangelizing Christians. Their idea is that even in a free society of this world such as the current social climate in America, people are controled by the need to improve their station in social circles, or in life in general. Also, in a more supernatural sence, they may argue that even in the best of societies, man is a slave to sin. In any case, their answer is, of course, to give your life to God. This will "free" you from sin, and also increase your social freedom in some supernatural sense, by making you part of something that is bigger than, and outside of this world.