(A witness that true believers are to express to a skeptical world is our bond of spiritual unity. Although we have many differences and denominations, all who have saving faith in the true Jesus are spiritually one in Him.)
Let us ﬁrst of all glance at the teachings (of Ephesians) here contained as to this unity of saints in Christ Jesus.
To begin with, the conception of Christ, as the sphere of all holy living, implies this unity. This sphere is invisible, however real, and our entrance into it and our abiding in it are not therefore matters of (physical) sense.Our place in it has to be obtained or received through the Spirit’s working, and recognized or perceived through the Spirit’s teaching. We must also recognize the place of other saints in the same sphere, by the same spiritual discernment. As we come into contact with true fellow believers and perceive in them the Christ image — as we see that they breathe the same air and live the same life, that they also belong to Christ and partake also of His Spirit, our conception of the unity of all believers in Him grows continually in vividness of impression.
We cannot help our love going out to them; to whatever different sphere they may belong, in family, social, or national life, they belong with usto that supreme sphere which is celestial (in the heavenlies Eph. 1:3) and eternal. And here is the only real hope of unity in the Church: it is found in the recognition ofour mutual relation to Christ, and in Him to each other — as our Lord prayed, “that they also may be one in us” (John 17:21)…
This unity in Christ is so prominent in this epistle that we must not lightly pass it by. Besides the general conception of Christ as the sphereof holy life, common to all these epistles (of the New Testament), we shall ﬁnd the following other ﬁgures used here to express the same thought:
1. The body of which He is the Head and we the members (1:22-23; 2:16; 4:12-16).
“And hath put all things under His feet, and gave Him to be the Head over all things to the church, which is His Body, the fulness of Him that ﬁlleth all in all” (Ephesians 1:22-23).
“And that He might reconcile both unto God in one body by the Cross, having slain the enmity thereby” (Ephesians 2:16; See 4:12-16).
2. God’s workmanship (2:10).
“For we are His workmanship, created in Christ Jesus unto good works, which God hath before ordained that we should walk in them” (Ephesians 2:10).] “Workmanship” is the Greek Poiema — same word as in Romans1:20: “For the invisible things of Him from the creation of the world are clearly seen, being understood by the things that are made (poema) , even His eternal power and Godhead; so that they are without excuse” (Romans 1:20) – a creation with a deﬁnite purpose, or object, and we, all, parts of that sphere of creation — “God’s poem.”
3. A commonwealth (2:12).
“That at that time ye were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of Promise, having no hope, and without God in the world” (Ephesians 2:12).  “Commonwealth” is politeia — a community in which we are citizens, introduced into it by the blood (2:19)…
4. A temple, with the middle wall of partition broken down (2:14).
“He is our peace.” Two courts — one.
“For He is our Peace, Who hath made both one, and hath broken downthe middle wall of partition between us” (Ephesians 2:14).
5. One new man (2:15).
“Having abolished in His ﬂesh the enmity, even the Law of commandments contained in ordinances; for to make in Himself oftwain One New Man, so making peace” (Ephesians 2:15).]
A very remarkable expression, nowhere else used.
6. One household of God (2: 19).
“Now therefore ye are no more strangers and foreigners, but fellowcitizens with the saints, and of the household (Greek, oikeios) of God” (Ephesians 2:19).] Oikeios, means “members of one household.”
…Christ is the sphere of all heavenly privilege and blessing. We have ﬁrst of all fellowship with Him, so that, “as He is so are we in this world.” We are so in Him that God looks on us only as in Him, as having been and done and borne and achieved all that He has Himself. In Him we are God’s elect, accepted, forgiven, redeemed, raised from the dead, sealed as His own, and seated with Him, in the heavenlies.
(May we embrace this spiritual connection and–as much as possible–walk in fellowship with our brothers and sisters in Christ.)
Part 1 of 2 is an excerpt of chapter 4 of In Christ Jesus, by A.T. Pierson (Originally published in 1898). (Sentences in parentheses added)
 1 John 4:17