Saint Theophan makes his point with several Scripture references.
"Seek ye the Lord and be strengthened; seek ye His face at all times. (Ps 104:4)
Paul reminds us,
For you are the temple of the living God. As God has said: “ I will dwell in them... (2 Cor 6:16)
Do you not know that you are the temple of God and that the Spirit of God dwells in you? (1 Cor 3:16)
“If anyone loves Me, he will keep My word; and My Father will love him, and We will come to him and make Our home with him. (Jn 14:23)
If anyone hears My voice and opens the door, I will come in to him and dine with him, and he with Me. (Rev 3:20)
I am in My Father, and you in Me, and I in you. (Jn 14:20)
Saint Theophan says this living unity with God is enlivening and God's goal for us.,
God's indwelling is not merely mental... but is a living, enlivening thing, to which contemplation should only be considered a means. Mental and heartfelt longing for God, that has come by God's good will, prepares a person to truly receive God. It is a kind of unity in which, without eradicating human strrength and personality, God manifests Himself as one that worketh in him both to will and to do (Phil 2:23); and the person, according to the Apostle, does not live but Christ lives in him (cf. Gal 2:20). This is not only the person's goal, but also the goal of God Himself.The Orthodox Way of life is about attaining this living unity with God. It is something we must continually work at. Its much more than a conversion experience. Such experiences are only the beginning of an Orthodox Christian life. This is when the real work begins. Knowing this indwelling God is a process of purifying our heart, purging our actions of all sinfulness. All this prepares us to receive His grace to align our will with His. This is our aim. This is the path to a truly virtuous life.