In any place where the gospel has been proclaimed and people have believed on the Lord, they are the church in that place, and they are our brethren.
How can we know who is a Christian and who is not? "If anyone does not have the Spirit of Christ, he is not of Him" (Rom. 8:9). According to the Word of God, every person in whose heart Christ dwells by His Spirit is a true Christian.
What is the secret of the oneness of the saints?
This mighty mysterious oneness is planted in the hearts of all believers the moment they receive the Lord. It is "the oneness of the Spirit" (Eph. 4:3).
We cannot make this oneness, since by the Spirit we are one in Christ, and we cannot break it, because it is an eternal fact in Christ; but we can destroy the effects of it, so that its expression in the Church is lost. Alas! that we have not only failed to preserve this precious oneness, but have actually so destroyed the fruits of it, that there is little outward trace of oneness among the children of God.
SEVEN FACTORS IN SPIRITUAL ONENESS
(1) ONE BODY(2) ONE SPIRIT(3) ONE HOPE(4) ONE LORD(5) ONE FAITH(6) ONE BAPTISM(7) ONE GOD (Eph 4)
The universal Church comprises all those who have the oneness of the Spirit. The local church comprises all those who, in a given locality, have the oneness of the Spirit.
-Take not of the following-
Anyone wishing to belong to a church in a given locality must answer two requirementshe must be a child of God, and he must live in that particular locality. Membership in the Church of God is conditioned only by being a child of God, but membership in a church of God is conditioned, firstly, by being a child of God and, secondly, by living in a given locality.
-The only division allowed in the church is GEOGRAPHICALLY.-
Every barrier between all believers in the world is avoidable, except this one.
Geographical distinctions are natural, not arbitrary, and it is simply because the physical limitations of the children of God make geographical divisions inevitable, that God has ordained that His Church be divided into churches on the ground of locality. Such division is scriptural, AND ALL OTHER DIVISIONS ARE CARNAL.
Most believers of today are so utterly blind to the scriptural basis of a church that if one asks another, "To what church do you belong?" The first thought of the one questioned is of the specific line of teaching he approves of, or the group of people with whom he has special fellowship, or how his group of Christians is different from others, or perhaps the name that particular group bears, or the form of organization they have adoptedin short, anything but the place in which he lives. Few would answer that question with, "I belong to the church in Ephesus," or "I belong to the church in Shanghai," or "I belong to the church in Los Angeles." It is our being in Christ that separates us from the world, and it is our being in a given locality that separates us from other believers. It is only because we reside in a different place from them that we belong to a different church. The only reason I do not belong to the same church as other believers is that I do not live in the same place as they do. If I wish to be in the same church, then I must change my residence to the same place. If, on the other hand, I wish to be in a different church from others in my locality, then the only solution to my problem is to move to a different locality. Difference of locality is the only justification for division among believers.
[The Normal Christian Church Life - Watchman Nee, (Chapter 8)]