Christ…, in His all-surpassing love for mankind, showed at Pentecost that His disciples were partakers, fathers and ministers of everlasting light and life, who bring us to new birth for eternal life and make those who are worthy children of the Light and fathers of enlightenment.
Thus, He Himself is with us unto the end of the world, as was promised through the Spirit (Matt. 28:20). For He is One with the Father and the Spirit, not according to hypostasis, but in His divinity, and God is One in Three, in one tri-hypostatic and almighty divinity.
The Holy Spirit always existed and was with the Son in the Father. How could the Father and divine Mind be without beginning if the Son and Word were not also without beginning? How could there be a pre-eternal Word without there also being a pre-eternal Spirit?
Thus the Holy Spirit ever was and is and will be, co-Creator with the Father and the Son, together with them renewing that which has suffered corruption, and sustaining the things that endure.
He is everywhere present and fills, directs and oversees everything. “Whither shall I go from thy spirit”, says the Psalmist to God, “Or whither shall I flee from thy presence?” (Ps. 139:7). He is ‘not just everywhere, but also above all, not just in every age and time, but before them all.
And, according to the promise, the Holy Spirit will not just be with us until the end of the age, but rather will stay with those who are worthy in the age to come, making them immortal and filling their bodies as well with eternal glory, as the Lord indicated by telling His disciples, “I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever” (John 14:16).
“It is sown”, says the Apostle (meaning buried and committed to the earth), “a dead natural body”, that is to, say, an ordinary created body with a created soul, stable and capable of movement.
“It is raised” (that is, comes back to life), “a spiritual body” (cf. 1Cor. 15:44), which means a supernatural body, framed and ordered by the Holy Spirit, and clothed in immortality, glory and incorruption by the Spirit’s power (cf. 1Cor. 15:53).
“The first man, Adam”, he says, “was made a living soul; the last Adam was made a quickening spirit. The first man is of the earth, earthy; the second man is the Lord from heaven. As is the earthy, such are they also that are earthy: and as is the heavenly, such are they also that are heavenly” (cf. 1Cor. 15:45,47-48).
Gregory Palamas (1296-1359): On Pentecost, 12-13 @Mystagogy.