The One Christ: St. Augustine's Theology of Deification
174 The Holy Spirit's Indwelling
Son, now poured out into the hearts of those who have become other Christs. This love is not a product of the Spirit but the indwelling of his holy presence. It is a love which transforms mutable minds and elevates creatures out of the disparateness of fallen reality and into the church, that preeminent creature where God is contemplated perfectly and unceasingly. This spiritual holiness allows us to see as God sees and to love as he loves.
Augustinian union is thus comprised of the Son's enfleshment, as well as the Spirit's personal indwelling in the human soul. The living unity, charity, and spiritual holiness between the Father and the Son are given to those who are being deified. The same Spirit vivifies and unifies not simply individuals but the body of believers Christ has gathered to himself. This is why we must next take up the notion of divine unity within Augustine's ecclesiology. The fullness of the Spirit comes only to those gathered in a unifying love: "The Lord has shown, in the eating of his flesh and the drinking of his blood, that we abide in him and he in us. But we abide in him when we are his members; but he abides in us when we are his temple. But that we may be his members, unity joins us together. That unity may join us together, what causes it except love?"96 As such, the Holy Spirit propels us ecclesially. The Spirit is sent to unite all peoples into one living body of praise, and the church is the living organ of the Trinity on earth, the one place where the sinner is not only forgiven but sanctified.
96. Jo. eu. tr. 27.6; Rettig, Tractates, 2.281.