Both of these images show Jesus (center), Mary the mother of Jesus (left), and John the Baptizer (right).
Orthodox churches have an iconostasis: a wall of icons and religious paintings that links together the nave from the sanctuary in a church. The door (called the Beautiful Gates) that the priest uses to move between the sanctuary and the nave is flanked by icons.
The bottom tier of icons is called the Sovereign. On the right side of the Beautiful Gates is an icon of Christ (often called Pantocrator –which means Almighty, Omnipotent, Lord of the Hosts). This image of Jesus symbolizes his Second Coming. On the left side is an icon of Mary the mother of Jesus, symbolizing Christ’s incarnation and entrance into this world. There is a theology behind these images. One side is Christ’s first incarnation, the other side is Christ’s second coming. All movement that takes place in the sanctuary during worship happens between Christ’s first and second coming.
John the Baptizer and Mary the mother of Jesus take their places beside Jesus as the primary examples of proclaiming and bearing the presence of Christ in the world. How do John and Mary strengthen our faith? One said, “I am not worthy to untie his sandals.” The other said, “I am the servant of the Lord, use me.” They model for us humility and service to the Messiah.
Advent is the season when we reflect on living between the first incarnation of Christ and his second coming. We remember his first coming into the world as a baby. And as we prepare for the coming of the infant Jesus, we are actually preparing for his second coming as the Ruler for all eternity.
(7) Finally, the icon has a liturgical function, it is a means of worship and veneration. This is one of its primary functions, more important than the first. Like sacred hymns and music, the icon is used as a means of worshipping God and venerating His saints. As such, it is essentially symbolic,leading the soul from the visible to the invisible, from the material to the spiritual, from the symbol to the prototype or original which it represents. As every Orthodox Christian knows, the first act of the faithful upon entering a church is to take a candle, light it and put it on a candlestand that is placed next to the proskynetarion or icon-stand on which is set the icon representing the sacred person, persons or event specially celebrated by the particular church and after whom or which it is named. Then he bows before the icon, making the sign of the cross, and kisses the icon, saying a brief prayer. This series of acts is called veneration or ‘honorable reverence’ of the icon. It is not an act of worshipping the icon. The Greek Church Fathers distinguish very sharply between ‘honorable reverence’ (timetike proskynesis),which is accorded to icons, and ‘worship’ (latreia).Worship is accorded only to God. Further, they emphasize that the veneration which we give to a holy icon goes to the prototype which it represents, for example, to Christ, to the Theotokos, to some martyr or other saint. In the words of Basil the Great, which have been repeated by John Damascene and other defenders of the icons, “the honor which is given to the icon passes over to the prototype” (he time tes eikonos eis to prototypon diabainei). The prototype honored is in the last analysis God, as God created man in His own image. 
Neither God nor the saints, of course, need the honor which we offer them, be it by means of icons, or by means of hymns and music. But it is only proper for us to do so, as the adoration of God and the admiration of saints are expressions of a soul that sees and loves the beauty of holiness, of spiritual perfection, and feels grateful to the Deity and to holy men for their many benefactions to mankind. Such a response is not merely something proper for us, but is also conductive to our salvation. The following remark of John Damascene calls attention to this point, and at the same time has a bearing on several of the functions served by icons: “I enter the common place-of-therapy of souls, the church, choked as it were by the thorns of worldly thoughts. The bloom of painting attracts me, it delights my sight like a meadow, and secretly evokes in my soul the desire to glorify God. I behold the fortitude of the martyr, the crowns awarded, and my zeal is aroused like fire; I fall down and worship God through the martyr, and receive salvation.”