This excerpt is taken from The Collected Writings of John Murray, Vol. 2: Systematic Theology, Chapter 23.

This progression (of sanctification) has respect, not only to the individual, but also to the church in its unity and solidarity as the body of Christ. In reality the growth of the individual does not take place except in the fellowship of the church as the fellowship of the Spirit. Believers have never existed as independent units. In God’s eternal counsel they were chosen in Christ (Ephesians 1:14); in the accomplishment of their redemption they were in Christ (2 Corinthians 5:14-15; Ephesians 1:17); in the application of redemption they are ushered into the fellowship of Christ (1 Corinthians 1:9). And sanctification itself is a process that moves to a consummation which will not be realized for the individual until the whole body of Christ is complete and presented in its totality faultless and without blemish. This points up the necessity of cultivating and promoting the sanctification of the whole body, and the practical implications for responsibility, privilege, and opportunity become apparent.

If the individual is indifferent to the sanctification of others, and does not seek to promote their growth in grace, love, faith, knowledge, obedience and holiness, this interferes with his own sanctification in at least two respects. 1) His lack of concern for others is itself a vice that gnaws at the root of spiritual growth. If we are not concerned with, or vigilant in respect of the fruit of the Spirit in others, then it is because we do not burn with holy zeal for the honor of Christ himself. All shortcoming and sin in us dishonors Christ, and a believer betrays the coldness of his love to Christ when he fails to bemoan the defects of those who are members of Christ’s body. 2) His indifference to the interests of others means the absence of the ministry which he should have afforded others. This absence results in the impoverishment of these others to the extent of his failure, and this impoverishment reacts upon himself, because these others are not able to minister to him to the full extent of the support, encouragement, instruction, edification and exhortation which they owe to him.

We see, therefore, the endless respects in which interaction and intercommunication within the fellowship of the saints are brought to bear upon the progressive sanctification of the people of God. “If one member suffers, all the other members suffer with it; and if one member is honored, all the others rejoice with it” (1 Corinthians 12:26). The truth of our inter-dependence within the solidarity of the body of Christ exposes the peril and contradiction of exclusive absorption in our own individual sanctification. How eloquent of the virtue which is the antonym of independence and aloofness are the words of the apostle: “And he (Christ) gave some apostles, and some prophets, and some evangelists, and some pastors and teachers, for the perfecting of the saints unto the work of the ministry, unto the edifying of the body of Christ; until we all come in the unity of the faith and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fulness of Christ”! (Ephesians 4:11-13; Romans 12:4ff.; 1 Corinthians 12:12ff.; Colossians 2:19).