Let him who does not pray expect nothing whatsoever from God- neither salvation nor renewal no direction nor grace. Rather, he is consigned to the whims and fancy of his own mind, the will of his own ego, and the direction of his own thinking. He is like one who has rejected the intervention of the Lord Jesus in his life, like one who hides himself from the Spirit of God. A man who does not pray is one who is content with his own condition. He wishes to remain as he is and not be changed, renewed or saved. His life unconsciously changes from bad to worse. He recedes spiritually day after day. The ties that bind him to the earth and to the flesh increase without his awareness. His ego remains the source of all his desires and ambitions.
As for his relationship with Christ, it remains only superficial and outward. It has no power to change or amend anything. The possibility to even deny Christ at times of danger, temptation, illness, or poverty becomes imminent.
So if man does not pray, he can never be changed or renewed, and he who is not changed or renewed can have no genuine or effective relationship with Christ. His worship, however active, is nothing but an outward protrusion or a superficial growth. In the end it breaks off, bearing no fruit.
* This excerpt is from “Orthodox Prayer Life: The Interior Way” by Fr. Matthew the Poor