First, I should point out that degrees of freedom are on a continuum. Total freedom and total bondage are generally not to be found. Freedom is the ability to do what you want, when you want to do it without penalties. (There is a difference between a consequence and a penalty. A consequence is a natural outcome of an action. A penalty is imposed from outside by people who don't like the action.) Most of us have to go to work, which is a constraint on freedom. But it's better than starvation.
Christians, for some reason that I cannot fathom, call complete bondage to "Jesus" their idea of "freedom." They say they do it willingly. My first guess is that this is in the same sense that I go to work willingly -- they think they get something out of it. But it would be more honest for them to say they exchange their freedom for something (whatever it is) that they want more. Maybe they don't desire freedom. But I don't think they should be using the word just because they think it sounds pretty.