From the day of Pentecost, to the present time, it has been their privilege, according to the promise, "I will pray the Father, and He shall give you another Comforter, that He may abide with you for ever,"—for ever: not like the Son of man, who having finished His gracious work went away. Then it is added, "even the Spirit of Truth:" that is, He who came for ever, came as a Spirit, and, so coming, did for His own that which the visible flesh and blood of the Son of man, from its very nature, could not do, viz., He came into the souls of all who believe, and taking possession of them, He, being One, knit them all together into one. Christ, by coming in the flesh, provided an external or apparent unity, such as had been under the Law. He formed His Apostles into a visible society; but when He came again in the person of His Spirit, He made them all in a real sense one, not in name only. For they were no longer arranged merely in the form of unity, as the limbs of the dead may be, but they were parts and organs of one unseen power; they really depended upon, and were offshoots of that which was One; their separate persons were taken into a mysterious union with things  unseen, were grafted upon and assimilated to the spiritual body of Christ, which is One, even by the Holy Ghost, in whom Christ has come again to us. Thus Christ came, not to make us one, but to die for us: the Spirit came to make us one in Him who had died and was alive, that is, to form the Church.

This then is the special glory of the Christian Church, that its members do not depend merely on what is visible, they are not mere stones of a building, piled one on another, and bound together from without, but they are one and all the births and manifestations of one and the same unseen spiritual principle or power, "living stones," internally connected, as branches from a tree, not as the parts of a heap. They are members of the Body of Christ. That divine and adorable Form, which the Apostles saw and handled, after ascending into heaven became a principle of life, a secret origin of existence to all who believe, through the gracious ministration of the Holy Ghost. 

Parochial and Plain Sermons volume 4/11