17.Sanctify them by thy truth. This sanctification includes the kingdom of God and his righteousness; that is, when God renews us by his Spirit, and confirms in us the grace of renewal, and continues it to the end. He asks, first, therefore, that the Father would sanctify the disciples, or, in other words, that he would consecrate them entirely to himself, and defend them as his sacred inheritance. Next, he points out the means of sanctification, and not without reason; for there are fanatics who indulge in much useless prattle about sanctification, but who neglect the truth of God, by which he consecrates us to himself. Again, as there are others who chatter quite as foolishly about the truth and yet disregard the word, Christ expressly says that the truth, by which God sanctifies his sons, is not to be found any where else than in the word.
Thy word is truth; for the word here denotes the doctrine of the Gospel, which the apostles had already heard from the mouth of their Master, and which they were afterwards to preach to others. In this sense Paul says that
the Church has been cleansed with the washing of water by the word of life,
True, it is God alone who sanctifies; but as
the Gospel is the power of God to salvation to every one that believeth,
whoever departs from the Gospel as the means must become more and more filthy and polluted.
The truth is here taken, by way of eminence, for the light of heavenly wisdom, in which God manifests himself to us, that he may conform us to his image. The outward preaching of the word, it is true, does not of itself accomplish this, For that preaching is wickedly profaned by the reprobate; but let us remember that Christ speaks of the elect whom the Holy Spirit efficaciously regenerates by the word. Now, as the apostles were not altogether destitute of this grace, we ought to infer from Christ’ words, that sanctification is not instantly completed in us on the first day, but that we make progress in it through the whole course of our life, till at length God, having taken away from us the garment of the flesh, fills us with his righteousness.