"17 Now this I say and testify in the Lord, that you must no longer walk as the Gentiles do, in the futility of their minds. 18 They are darkened in their understanding, alienated from the life of God because of the ignorance that is in them, due to their hardness of heart. 19 They have become callous and have given themselves up to sensuality, greedy to practice every kind of impurity. 20 But that is not the way you learned Christ!— 21 assuming that you have heard about him and were taught in him, as the truth is in Jesus, 22 to put off your old self,[f] which belongs to your former manner of life and is corrupt through deceitful desires,23 and to be renewed in the spirit of your minds, 24 and to put on the new self, created after the likeness of God in true righteousness and holiness."
Ephesians 4:17-24
What was said at the end of the previous Note serves to explode one of the confident clichés often heard today, namely that 'Christianity is not a negative thing, but a positive one'. And the answer Paul gives is: 'Of course there are negatives, as well as positives, in the Christian faith'. And he does not allow anyone to forget it, nor is this the only place he emphasises this fact, for it is evident all through his epistles, as for example in the well-known statement in 1 Thessalonians 4:3, 'This is the will of God, even your sanctification, that ye should abstain ....' How can anyone say that 'Christianity does not say "You mustn't do this, you mustn't do that" when that is exactly what Paul does say in that verse in Thessalonians.' The truth of the matter is that there are both negatives and positives involved, and so often the negatives are a necessary 'first' before the positives can become possible. It is the 'negatives' that we are particularly concerned with - 'walk not', 'put off the old man', 'sin not, 'steal no more', 'no corrupt communication', 'grieve not'.
The 'negatives' Paul uses in these verses are summed up in the phrase 'the old man', and the 'positives' in the phrase, 'the new man' and, he says, we are to put off the old man and put on the new. And it is always a case of 'identifying' the evidences of the old man, putting them off, shunning and turning from them; and likewise 'identifying' the attributes of the new man, putting them on and living as new men in Christ. This is a fundamental and decisive part of Paul's teaching in all his epistles, and central to his doctrine of sanctification. And it is something that every Christian must grapple with, to understand it and know its virtue in his life. This is not easy, but then, what is easy that is worthwhile and vital in Christian experience? It is abundantly worth it to make the effort and get down to it.