Verses 1, 2, 3

The apostle does not speak of obedience, but of the Spirit which leads to it; the practical effect of the presence of God by the Spirit, is humility. Love always makes itself nothing. To have bad thoughts about oneself is humiliation, but not humility. Humility is produced by the presence of God; we are occupied with God and not with ourselves; God is there to comfort us and to bless us; the pride of man being broken down there is gentleness. This making nothing of oneself produces patience and love. When we know ourselves to be nothing, we have the consciousness of the strength of God; and more than that, there is the activity of love.
Consciousness of the preciousness of the presence of God, gives us the energy of the Spirit of God, which makes us careful to keep the oneness of the Spirit, that is to say, the union of all the members of Christ as one temple in which God dwells in this world by His Spirit. The moment that I forsake this, the unity is broken. In the flesh we are two, in the Spirit we are one; and when, by the Spirit, we enjoy love, there is this desire to keep the oneness of the Spirit. The flesh is never peaceful, whereas in God all is peace and quietness.
It is remarkable how often God is called the God of peace (see Phil. 4:9; 1 Thess. 5:23; Heb. 13:20). The bond of peace is indeed the result of being thus in the presence of God; it is on this account that the apostle adds, " There is one body and there is one Spirit." Oneness is a thing which is actually realized on earth, the outward unity of the body in one expresses what there is within. If this bond of peace is wanting, the oneness of the Spirit is not kept.
Verse 4.
Paul turns back to the thought put forth in the first chapter, "The hope of glory." This same Spirit which has given the same hope, has given the oneness of the body; this outward unity which manifests the Spirit as well as oneness in the glory. There is but one body here below.