Spiritual unity with God and other believers

All of us who have received one and the same Spirit, that is, the Holy Spirit, are in a sense blended together with one another and with God. For if Christ, together with the Father's and his own Spirit, comes to dwell in each of us, though we are many, still the Spirit is one and undivided. He binds together the spirits of each and every one of us, ... and makes all appear as one in him. For just as the power of Christ's sacred flesh unites those in whom it dwells into one body, I think that in the same way the one and undivided Spirit of God, who dwells in all, leads all into spiritual unity.
St. Cyril of Alexandria, In Jo. ev., 11,11:PG 74,561.
St. Cyril is honored in the Lutheran, Anglican, Oriental Orthodox, Eastern Orthodox and Roman Catholic churches. He lived c. 376 – 444. He was involved in many church controversies during his live.