14 But when I saw that their conduct was not in step with the truth of the gospel, I said to Cephas before them all, “If you, though a Jew, live like a Gentile and not like a Jew, how can you force the Gentiles to live like Jews?”
15 We ourselves are Jews by birth and not Gentile sinners; 16 yet we know that a person is not justified by works of the law but through faith in Jesus Christ, so we also have believed in Christ Jesus, in order to be justified by faith in Christ and not by works of the law, because by works of the law no one will be justified.
17 But if, in our endeavour to be justified in Christ, we too were found to be sinners, is Christ then a servant of sin? Certainly not! 18 For if I rebuild what I tore down, I prove myself to be a transgressor. 19 For through the law I died to the law, so that I might live to God. 20 I have been crucified with Christ. It is no longer I who live, but Christ who lives in me. And the life I now live in the flesh I live by faith in the Son of God, who loved me and gave himself for me. 21 I do not nullify the grace of God, for if righteousness were through the law, then Christ died for no purpose.
The important doctrinal statement contained in these verses is fundamental to Paul's teaching in all his epistles, and we must pay close attention to what he says. A single glance at the verses will show that the Apostle is dealing with the doctrine of justification by faith apart from the works of the law. But the impressive thing to see is the way in which he brings in another doctrine into the reckoning - that of our union with Christ in His death and resurrection (20), which lies at the heart of the biblical understanding of sanctification. How naturally - and inevitably - he passes from one to the other! Indeed, there is a sense in which he deals with them both at the same time. This does not mean that they are identified with one another, or confused - Paul was much too precise a theologian for that - but it does mean that the one is implied in the other in the sense that there is no such thing as an experience of justification that is not at the same time the beginning of sanctification. Indeed, for Paul, justification involved the death of which he speaks in 20: 'I have been crucified with Christ'. For Paul the faith that justifies is a faith with a death in it. Justifying faith also crucifies! The experience of being crucified with Christ certainly did not, for Paul, belong to a further stage of Christian advancement after justification. On the contrary, he teaches that crucifixion with Christ is that initial form of consecration which takes place when by faith we lay hold of the justifying mercy offered us in the gospel invitation. Until we understand this to be so, we shall never emerge from the welter of confusion that surrounds the present-day exposition of the doctrine of sanctification.