What I had never quite appreciated before is the extent to which a certain kind of Evangelicalism seems to resemble a purity cult, not unlike that of the Pharisees or the Essenes.
His reflections on the first Christmas and the ministry of Jesus make a lot of sense.
In Jesus' ministry holiness seems hardly ever to be about separating oneself off from 'the world'. In dramatic contrast, holiness, the state of being clean before God, is something that Jesus confers upon people. In his ministry to lepers uncleanness does not flow from the leper to the one touching the leper, as taught by the Pharisees, but cleanness flowed to the leper from Jesus.
This process of holiness flowing from God to us is endorsed in a number of places through the New Testament including this in Hebrews;
"...we have been made holy through the sacrifice of the body of Jesus Christ once for all." Heb 10:10
I'm glad it's Jesus that makes me holy - I'd sure stuff it up if it was left to me. And it's that assurance of holiness that draws me back again and again to purity as a response to his amazing gift.
"So also Jesus suffered and died outside the city gates to make his people holy by means of his own blood. So let us go out to him, outside the camp, and bear the disgrace he bore. For this world is not our permanent home; we are looking forward to a home yet to come." Heb 13:12-14
Scripture would suggest that our holiness is not challenged by engagement with the world - but, if we're living right with God, the world may be challenged by our holiness.