Cathal BarryHow is the Son of God man, the Catechism of the Catholic Church asks at a point.
According to the Church, this is because ìhuman nature was assumed, not absorbedî, in the mysterious union of the Incarnation, the Church was led over the course of centuries to confess the full reality of Christ's human soul, with its operations of intellect and will, and of his human body.
In parallel fashion, she had to recall on each occasion that Christ's human nature belongs, as his own, to the divine person of the Son of God, who assumed it. Everything that Christ is and does in this nature derives from "one of the Trinity".
The Catechism notes that Apollinarius of Laodicaea asserted that in Christ the divine Word had replaced the soul or spirit. Against this error the Church confessed that the eternal Son also assumed a rational, human soul.
This human soul that the Son of God assumed, according to the Church, is endowed with a true human knowledge. As such, this knowledge could not in itself be unlimited: it was exercised in the historical conditions of his existence in space and time.
This is why the Son of God could, when he became man, "increase in wisdom and in stature, and in favour with God and man", and would even have to inquire for himself about what one in the human condition can learn only from experience. This corresponded to the reality of his voluntary emptying of himself, taking "the form of a slave".
At the same time, however, this truly human knowledge of God's Son expressed the divine life of his person. According to St Maximus the Confessor: "The human nature of God's Son, not by itself but by its union with the Word, knew and showed forth in itself everything that pertains to God." Such is first of all the case with the intimate and immediate knowledge that the Son of God made man has of his Father.
The Son in his human knowledge also showed the divine penetration he had into the secret thoughts of human hearts.
By its union to the divine wisdom in the person of the Word incarnate, Christ enjoyed in his human knowledge the fullness of understanding of the eternal plans he had come to reveal. What he admitted to not knowing in this area, he elsewhere declared himself not sent to reveal.
Similarly, at the sixth ecumenical council, Constantinople III in 681, the Church confessed that Christ possesses two wills and two natural operations, divine and human. They are not opposed to each other, but co-operate in such a way that the Word made flesh willed humanly in obedience to his Father all that he had decided divinely with the Father and the Holy Spirit for our salvation. Christ's human will "does not resist or oppose but rather submits to his divine and almighty will".