That the Gentiles were to be saved was no mystery. Rom. 9:24-30. The "Mystery" was, that God was going to form an entirely "NEW THING," composed of Both Jew and Gentile, to be called-"THE CHURCH."
2. It is a "Called Out" Body.
The word Church comes from the Greek word "ecclesia" which means "Assembly" or a congregation of "called out ones."
But the word is not used exclusively as to the Church. Israel was an "ecclesia" or an Assembly of people "called out" from other peoples and nations, and is called in Acts 7:38, "The Church in the Wilderness."
Any Assembly of worshippers banded together as a church or congregation is an "ecclesia." Matt. 18:17; I Cor. 14:19,35.
The purpose of this Dispensation is seen in the "Divine Program," outlined by the Apostle James in his address to the First Church council (Acts 15:13-18), where he declares that God has visited the Gentiles to
"Take Out of Them A 'PEOPLE' for His Name."
The purpose of this Dispensation then is not the Conversion of the World, but the "Gathering Out" of the Church.
While Israel is a "called out body" it is a "National Body," composed exclusively of the descendants of Abraham, but the Church is not a "National Body" for it is not composed of the people of any one nation, but of individuals from every kindred, people, tribe and nation.
That Israel and the Church are distinct and separate and cannot be blended, is clear from the fact that their "election" was made at different dates, and that the "election" of the Church antedates the "election" of Israel, for Israel was chosen in Abraham from the foundation of the world (Matt. 25:34), while the Church was chosen in HIM (Jesus) BEFORE the Foundation of the World. Eph. 1:4-6
3. It is the "Body of Christ." In Eph. 1:22,23 we read:
(22) And He put all things under His feet, and gave Him to be head over all things to the church,
(23) which is His body, the fullness of Him who fills all in all.
The context shows (vs. 20), that this "Headship" was not possible until Jesus had been raised from the dead, and seated at the right hand of the Father. The Church, therefore, could not have been in existence before there was a Head, for God does not make headless things. The Church then is the Body of which Christ is the Head.
In I Cor. 12:12,13 we are told how this "Body" is formed.
"For as the body is one, and hath many members; and all the members of that one body, being many, are one body; so also is Christ. For by one Spirit are we all baptized into One Body, whether we be Jew or Gentile, whether we be bond or free; and have been all made to drink into ONE SPIRIT."
From this we see that it is the "Baptism of the Spirit" that incorporates us into the "BODY OF CHRIST."
Therefore there could be no Church until the "Day of Pentecost." Acts 1:4,5; 2:1-4.
The fact that the Church is a "Body" made up of "living members" shows that it is not an "Organization," but an "ORGANISM." An "Organization" is made up of distinct units like the doors, windows, roof, floors, etc., of a building, that may be removed and replaced by new parts without destroying the integrity of the building; but a human body is an organism. You cannot remove an eye, or ear, or arm, or foot, or even a finger nail or tooth, without destroying the integrity of the body and causing a mutilation. So we see from this for Christ to lose One Member of His Body (the Church) is to MUTILATE it.
Neither can the Church, as the "Body of Christ" die, for who ever saw a dead body attached to a living head. Christ the Head is ALIVE and can NEVER DIE AGAIN, for He tells us in Rev. 1:18, "I am He that liveth and was dead (on the Cross), and behold, I am ALIVE FOR EVERMORE." It follows therefore that "when Christ, who is our LIFE, shall appear, then Shall We Also Appear With Him in Glory." Col.3:4. Jesus Christ not only gave His life for the Church, but to the Church.
But why call the Church the "Body of Christ?" What is a body for? It is for the
Manifestation of a Personality.
A person can exist without a physical body, as the Soul exists without a physical body between death and the resurrection of the body, but that existence cannot be made manifest. So the only way Christ, who is now in glory, can manifest Himself to the world is through His Body THE CHURCH.
The only way the world can see Christ today is in Christian believers. This is probably what Paul meant when he wrote to the Philippians,
"For to me to live Is Christ."