Webster’s defines UNION as “a uniting or being united; a putting together or joining together so as to make one;
a combination, bringing together in a common cause.”
One type of UNION would be a marriage.
A union is a joining together to make one. When we were "born-again" we were put into a living UNION or connection with Father God. Christ enabled us to be a partaker of the inheritance of the saints in Life. (Colossians 1:12)
The connection in our UNION with Christ is the New Birth.
(GOOD NEWS) You were baptized into union with Christ, and so have taken upon yourselves the qualities of Christ himself.
(WAY) Yes, all of you have have by baptism passed into union with Messiah have clothed yourselves with Messiah's personality.
(BARCLAY) For all those who have become one with Christ through baptism are, as it were, clothed with the life of Christ.
(GREBER) For by baptism you have become spiritually merged with Christ, and his spiritual garment envelops you.
If we have been baptized or immersed into Christ (this is done by the Holy Spirit when one confesses Jesus as Lord), we become one with Him.
When a man becomes a New Creation in Christ by confessing Jesus as Lord, according to Romans 10:9-10 he immediately comes into UNION with Christ.
(WILLIAMS) Whoever owns that Jesus is the Son of God, God remains in that union with him and he in union with God.
(AMPLIFIED) . . .God abides (lives, makes his home) in him, and he (abides, lives, and makes his home) in God.