Ephesians 4:17-19

Verse 17 makes it abundantly clear that even though we are saved by grace through faith, completely as a result of God's kindness, it certainly does matter how we live. When we come to Christ we must live a different life. The reason given here is that the way the world lives is a result of futile thinking. The world basically hasn't got a clue. At the moment the world is in the midst of a financial crisis, much of this is the result of people following supposedly clever advise, by banks over borrowing so that they could supposedly make better use of money, of high flyers needing to be paid ridiculous amounts of money because if we didn't do this they would go somewhere else (if only they had!). All this wisdom has been shown to be nonsense.

The same applies to world's supposed wisdom on relationships and sexual practices. The world's way leads to increase in various diseases, and more importantly harms people's emotions. There is precious little evidence that the world's way does anything to increase the sum total of human happiness.

The reason for all this is that the world is separated from God, and so form the life of God. Only God knows the way of life, only Jesus is the way of life. When people become separated from God their hearts become hardened and they descend into increasing ignorance. They lose sensitivity, ie sensitivity to God, sensitivity to the needs and feelings of other people, and even sensitivity to what is happening to themselves. They become self-centred seeking ever more sensual satisfaction in a futile effort to fill the void.