The Orthodox Church observed the Great Feast of Pentecost on June 23rd. Celebrated on the Seventh Sunday (50 days) after Pascha and 10 days after the Ascension of the Lord, Pentecost -- also referred to as Trinity Sunday -- marks the descent of the Holy Spirit on about 120 disciples.
The Gospel reading (John 7:37-52; 8:12) for the feast describes Christ's promise of Pentecost while the Epistle reading (Acts 2:1-11) describes the unity of assembling "with one accord in one place... [a]nd they were all filled with the Holy Spirit."
While the Church pre-existed creation and time, Her Salvific mission in the revelation as the body and blood of Christ begins on this day by receiving its first converts, "about three thousand souls" writes Luke the Evangelist (Acts 2:41).
Still, the word 'church' is so loosely used in our day that it seems any organization led by any individual can be considered one. Jesus Christ, the only-begotten Son of God, Founded and is continuously present in the Church, "lo, I am with you always," He said (Mt 28:20), "from whom the whole body [is] joined and knit together" (Eph 4:16).
"There is one body and one Spirit, just as you were called in one hope of your calling; one Lord, one faith, one baptism; one God and Father of all, who is above all, and through all, and in you all" (Eph 4:4-6).
As referenced above, according to St. Paul, the Church is the body and blood of Christ and through it Christians are united to Him and to each other in the ark of salvation. The unity between the God-Man (Theanthropos, in Greek) Christ and His Church is binded by, and through, the sacraments, especially Holy Communion.
Immediately following the baptism of an Orthodox Christian, for example, the newly baptized receives the gift of the Holy Spirit (which proceeds from the Father and not from the Father and Son as some say) through chrismation.
Therefore, the idea of "Churchless Christianity" is not only in opposition to Holy Scripture and the teachings of the Apostles and Church Fathers but it is also dangerous for believers. St. Cyprian the Hieromartyr and Bishop of Carthage says, "A person cannot have God as his Father if he does not have the Church as his Mother."
The four signs of the Church as expressed in the Nicene Creed -- the most universal confession of faith in Christendom -- are One, Holy, Catholic and Apostolic: the unity of the Church; its sanctity through the presence in it of the Holy Spirit; the universality and whole of the Christian message; and, Apostolic succession are the fundamental pillars of the true Church. Valid continuity in the Priesthood is essential as it allows for the Divine legacy of the apostles to continue and eliminates the possibility of private, man-made theology.
Quoting St. John Chyrsostom, St. Nikolai Velimirovich describes how the Church represents the realm of the holy:
Why is it necessary to listen to the Church and not to a man who thinks against the Church, even though he might be called the greatest thinker? Because the Church was founded by the Lord Jesus Christ and is guided by the inspiration of the Spirit of God; because the Church represents the realm of the Holy, a grove of cultivated fruit trees. If someone rises up against the realm of the Holy, it means that he is unholy. Why then listen to him? "The Church is an enclosure," says the all-wise John Chrysostom. "If you are within, the wolf does not enter; but if you leave, the beasts will seize you. Do not distance yourself from the Church; there is nothing mightier than the Church. The Church is your hope. The Church is your salvation. The Church is higher than the heavens. The Church is harder than stone. The Church is wider than the world. The Church never grows old but always renews itself.
Moreover, in his 2006 book, "Theosis: The True Purpose of Human Life," Archimandrite George - Abbot of the Holy Monastery of Saint Gregorios (Mount Athos) -- writes:
So, being baptised, chrismated, confessing, we commune through the Body and Blood of the Lord, and we too become gods by Grace; we unite with God; we are no longer strangers, for we have become familiar with God. Inside the Church in which we unite with God, we live this new reality which Christ brought to the world: the new creation. This is the life of the Church, of Christ, which becomes ours as a gift from the Holy Spirit. Everything in the Church leads to Theosis; the Holy Liturgy, the Mysteries [Sacraments], divine Worship, the Gospel sermon, the fasting; all of these lead to this one thing. The Church alone is the place of Theosis.
The Orthodox Church is in truth a hospital whose tradition is therapeutic in character and whose chief concern is healing the human soul.
The core of the Holy Tradition is purification, illumination and glorification [Theosis]. We stress the importance of illumination, which follows purification and precedes divine vision, because illumination, participation in the illuminating energy of God, forms the basis for participation in the energy of God that enables us to see Him (Empirical Dogmatics of the Orthodox Catholic Church, Metropolitan of Nafpaktos Hierotheos).
This revelatory process and gift from God present within the Church can lead us to our own Pentecost. Christ Ascended into Heaven and sent us the Holy Spirit so that we could become gods by grace. St. Athanasios, Patriarch of Alexandria, says, "God became human that we might be made god."
For this reason, the Sunday immediately following Pentecost the Church commemorates All Saints, known and unknown, which, as shown at Pentecost, is the ultimate purpose of Christians: to become saints through the grace of the Holy Spirit.
Amen and Glory be to God.