The following excerpt comes from the great Helmut Thielicke's sermon "The Parable of the Prodigal Son." Here he is talking about when the son comes to himself in the pigsty.

Now for the first time he begins to realize what it means not to be with the father, no more to be a son. so this is the end of his freedom, his autonomy, and whatever other glittering terms one may use.

The fact is, of course, that we are always subject to one master. Either to God, and then we are in the Father's house, possessing the freedom of the children of God, sons and not servants, with constant access tot he Father. Or we are subject to our urges and therefore to ourselves, subject to our dependence on men, subject to our fears - with which our hearts are always well supplied - our worries, our Mammon.

There is no such thing as neutrality between these two masters. And we begin to surmise what Luther was saying when he spoke of our human life as a battlefield between these two masters. We are not masters at all, as the prodigal son wanted to be; we are only "battlefields" between the real masters. In other words, the question we face is whether we want to be the child of the one or the slave of the other.

"I wanted to be free," says the prodigal son to himself - perhaps he cries it aloud, "I wanted to become myself; and I thought I would get all this by cutting myself off from my father and my roots, fool that I am! I have found nothing but chains!" And bitter laughter goes up from the pigsty.

That he should have wanted to separate himself from his father now seems just as ridiculous as that a person should fret over being dependent on air and then hold his breath in order to assert his freedom. We cannot with impunity - actually, without being utterly foolish - separate ourselves from the element in which we live and have our being. We can't take God off as we would take off a shirt. To separate ourselves from the Father is at bottom not merely "unbelief" at all, but simply the most monstrous kind of silliness.