Our communion in the divinity of Christ means our union with the Trinity, which in its turn allows the divine nature to pervade and permeate us, just as fire heats a piece of iron and makes it glow. All we have to do after believing in Christ and discovering our communion with him is to give the divine, ineffable beauty of the nature of the Trinity the chance to dawn within us, to glow and to shine.
Ascetical struggle is nothing but an attempt to be in conformity with the Holy Spirit, which is actually within us, and to be in harmony with the thought of Christ, which actually fills us. The Holy Spirit, which God gives us as soon as he dwells in us, qualifies us for aquiring the likeness of Christ, and consequently, we become a real image of the Father. When we acquire the likeness of Christ by the indwelling of the Holy Spirit in us, we become “sons of partnership,” and when we partake of the divine nature as sons with Christ we become in union with God through the Holy Spirit.
Excerpt taken from the book: Orthodox Prayer Life, By Matthew the Poor