The following is taken from: "The Divine Liturgy Explained", by Rev. Nicholas M. Elias

In the Divine Liturgy our Lord is present: first in the person of His priest, secondly, in His Word which is read in the Church, and thirdly, according to His promise; “Where two or three are gathered in My name, there am I in the midst of them.” (Matt. 18:20). Lastly, He is really and truly present upon the altar under the appearances of the consecrated Bread and Wine.

The Divine Liturgy is divided into several parts, each corresponding to a particular event of our Lord’s Life. Before every Divine Liturgy the Offertory (Proskomide) is prepared for consecration by the Priest, during the Matins service without being seen by the congregation, just as Christ’s early Life was not shown (Matt. 11:27, John 14:9). This part of the Liturgy commemorates Christ’s early Life, which was a preparation for His public ministry.

The Liturgy is divided into 2 parts:
1) The Preparation, which ends after the Creed. This part corresponds to our Lord’s Life during His public ministry. It is a representation of the most important events of His Life; His coming to the world (The Entrance of the Gospel), His teaching (readings from the Epistle and Gospel), His death and burial (The Great Entrance) His Resurrection (indicated by the shaking of the “Aer” over the holy Gifts during the recitation of the Creed by the phrase “and rose on the third day”), and His Ascension to Heaven (indicated byt the phrase “And ascended into Heaven”).

2) The Sacramental Part, which begins with the exhortation of the deacon or the priest: “Let us stand well” let us stand with fear” (Stomen Kallos, Stomen Meta Fovou) This part of the Divine Liturgy is the most sacred, because in it the Sacrament of Holy Eucharist is consummated. These two parts of the Divine Liturgy are so closely connected with each other that they form but one single act of worship. This is why the Liturgy should be attended in its entirety, not as duty but as a distinct privilege.

The Divine Liturgy, although its intention is primarily for man to worship God and to give thanks to Him, also showers actual grace and blessings upon those in attendance to aid them as the Lord’s chosen people. There, in the atmosphere of the worship, a spiritual renewal comes to each of them from the higher thoughts the Liturgy suggests to them, from the sacred hymns, from the reading and teaching of the Gospel, from prayer, and from the Grace of our Lord, Who is actually present in the Divine Liturgy.

Worshipping together is very beneficial also. It strengthens the faith of each one and lifts one, as in no other possible way, into the very presence of God. Thus the sprit of each worshipper soars upward into the realm of inspirational thought and purpose, which cannot be reached in any other atmosphere or relationship. The mind and heart of each becomes responsive to the influences that make him a receiver of and instrument for witnessing to righteousness, benevolence and truth. During the six days of the week, our work, earthly cares, worries, anxieties and disappointments, temptations and provocations to sin, all these worldly things, exhaust us spiritually and physically.

But God, in His infinite mercy provides us with Sunday, the day of the Lord, when by going to Chruch, we are supplied with new spiritual and moral nourishment for our needs for the coming week. When God, in his wisdom set apart one day out of every seven and hallowed it as His own day, He was not thinking of any need to be worshipped, but of our need for renewal of our spiritual energies. Therefore, attending Church on Sunday is like the winding of a clock. Spiritual life cannot go too long without “rewinding”. By attending the Divine Liturgy Sunday after Sunday we are equipped spiritually and morally for whatever lies ahead. All these benefits and blessings are conferred upon us in even greater abundance when we partake of Holy Communion. This is the purpose of the institution and consummation of the Holy Eucharist. Holy Communion, being divine food and medicine, affords our souls nourishment, growth, strength, health, and even more important, eternal life. It is also safeguard and cure for the ills of our bodies, because the abundance of Grace, with which Holy Communion enriches the soul, is also communicated by it to the body, which is so intimately united with the soul. The Grace that the soul receives exercises wholesome influence on the body, whose sensual nature is consequently weakened.

Partaking of Holy Communion as often as possible, we really partake of Christ’s Life, so that our lives might be transformed into the very likeness of His Life (John 6:54-56). Christ’s Life, which is imparted to us through reception of Holy Communion, removes the barriers which separate the poor from the rich, the ignorant from the learned, the unfavored from the favored, and thus strengthens the bonds of Christian love and harmony among all men (I Corinth. 10:17).

However, there are people who attend the Divine Liturgy and receive Holy Communion regularly, yet they receive little or no benefit from it. Why? Because they do not fulfill the necessary requirements for attending the Divine Liturgy and receiving Holy Communion properly. It is similar to student in a classroom who does not pay attention to what the teacher says and never does his homework. He gets very little out of school. Likewise, those who arrive late to church and do not understand the meaning of Divine Liturgy; or those who are hypocrites in their lives, and those who go to church as mere spectators, or to hear the choir, or to indulge passively in praise and prayer much as they go to see a ball game; all such people cannot be fully benefited from the Divine Liturgy. The worshippers whoa re richly blessed by attending the Divine Liturgy are those who are present for the entire Liturgy and who follow it with understanding; those who are sincere and well disposed to it, and those who receive Holy Communion only after being properly prepared and approach the altar “With fear of God, with faith and love”.