Man, according to the scriptures, is created “in the likeness of God” (Gen 1:26-27). To be like God, through the gift of God, is the essence of man’s being and life. In the scriptures it says that God breathed into man, the “breath [or spirit] of life” (Gen 2:7). This divine teaching has given rise to the understanding in the Orthodox Church that man cannot be truly human, truly himself, without the Spirit of God. Thus Saint Irenaeus (3rd c.) said in his well-known saying, often quoted by Orthodox authors, that “man is body, soul, and Holy Spirit.” This means that for man to fulfil himself as created in the image and likeness of God—that is, to be like Christ who is the perfect. divine, and uncreated Image of God—man must be the temple of God’s Spirit. If man is not the temple of God’s Spirit, then the only alternative is that he is the temple of the evil spirit. There is no middle way. Man is either in an unending process of life and growth in union with God by the Holy Spirit, or else he is an unending process of decomposition and death by returning to the dust of nothingness out of which he was formed, by the destructive power of the devil. This is how the Orthodox spiritual tradition interprets the “two ways” of the Mosaic law:
I call heaven and earth to witness against you this day, that I have set before you life and death, blessing and curse, therefore choose life that you and your descendants may live, loving the Lord, obeying His voice and cleaving to Him, for that means life to you (Dt 30:19-20).
It is this same teaching that the Apostle Paul gives in his doctrine of the “two laws” at work in the life of man.
For I delight in the law of God in my inmost self, but I see in my members another law at war with the law of my mind and making me captive to the law of sin which dwells in my members. [...] For the law of the Spirit of life in Christ Jesus has set me free from the law of sin and death. [...] For those who live according to the flesh set their minds on the things of the flesh, hut those who live according to the Spirit set their minds on the things of the Spirit. To set the mind on the Spirit is life and peace (Rom 7:14-8:17).
Every human being is confronted with these two possibilities, ultimately the only two possibilities of human existence. Either a person chooses life by the grace of God and the power of the Spirit—the “abundant” and “eternal life” given by God in creation and salvation through Jesus Christ—or the person chooses death. The whole pathos of human existence consists in this choice, whether a person is aware of it or not. Christian spiritual life depends on the conscious choice of the “way of life.” To “choose life” and to walk in the “way of life” is the way that man shows himself to be in the image and likeness of God.
For by the hands of the Father, that is by the Son and the Holy Spirit, man, and not merely a part of man, was made in the likeness of God… for the perfect man consists in the commingling and the union of the soul receiving the Spirit of the Father and the fleshly nature which was also moulded after the image of God… the man becomes spiritual and perfect because of the outpouring of the Spirit, and this is he who was made in the image and likeness of God.
If in a man the Spirit is not united to the soul, this man is imperfect. He remains animal and carnal. He continues to have the image of God in his flesh, but he does not receive the divine likeness through the Holy Spirit (St Irenaeus, 2nd C., Against Heresies).