III. The union of the Divine Head with Its members inseparable
There is no doubt therefore, dearly-beloved, that man's nature has been received by the Son of God into such a union that not only in that Man Who is the first-begotten of all creatures, but also in all His saints there is one and the self-same Christ, and as the Head cannot be separated from the members, so the members cannot be separated from the Head. For although it is not in this life, but in eternity that God is to be “all in all,” yet even now He is the inseparable Inhabitant of His temple, which is the Church, according as He Himself promised, saying, “Lo! I am with you all the days till the end of the age.” And agreeably therewith the Apostle says, “He is the head of the body, the Church, which is the beginning, the first-begotten from the dead, that in all things He may have the pre-eminence, because in Him it was pleasing that all fullness (of the Godhead) should dwell, and that through Him all things should be reconciled in Himself.”
Source: Sermons (New Advent)