People who were brought up within legalistic structures – those faith-poisoning, faith-sterilizing structures – often have an eagle eye for judgmental attitudes, zero tolerance for sanctimony, and a tendency to reject rules, as well as any critical remarks.
It is hard sometimes for us to walk the path away from legalism without losing ourselves in the opposite lie, libertinism.
Paul the apostle – fierce enemy of legalism, fierce advocate of genuine Gospel life – has been my best help along this path. In his commentary on the letter to the church in Corinth, Gordon D. Fee describes Paul’s understanding of Christian ethics as “becoming what you are”. And, as he says:
In such ethics there are some absolutes, precisely because some sins are quite incompatible with life in Christ ([e.g.] sexual immorality). This is not law, in the sense of gaining right standing with God. But it is absolute since some behavior is absolutely contradictory to the character of God. 
Christian ethics are not about rules and regulations. Instead, they are about reflecting the character of God – about belonging more and more to the New Creation.
In an age in which ethics is too often modified to fit one’s present cultural existence, these words need once more to be heard distinctly in the church. Christ has died for us not simply to give us passage to heaven but to re-create us in his own image, so that both individually and corporately we may express the character of God by the way we live in [the] world. 
Legalism is a lie. Libertinism is a lie. “In Christ, the new creation has come: The old has gone, the new is here!”
 Gordon D. Fee, The First Epistle to the Corinthians