We believe in one God, the Father Almighty, Maker of heaven and earth and of all things visible and invisible;
And in one Lord, Jesus Christ, the Son of God, the Only-Begotten, begotten of the Father before all ages;
Light of Light, True God of True God, begotten, not made, of one essence with the Father, by whom all things were made;
Who for us men and for our salvation came down from heaven and was incarnate of the Holy Spirit and of the Virgin Mary and became man;
And was crucified for us under Pontius Pilate and suffered and was buried;
And resurrected on the third day, according to the Scriptures;
And ascended into heaven and sits at the right hand of the Father;
And He will come again in glory to judge the living and the dead;
Whose kingdom will have no end;
And in the Holy Spirit, the Lord, the Giver of Life, who proceeds from the Father, who together with the Father and the Son is worshipped and glorified, who spake by the prophets.
We believe in one, holy, catholic, and apostolic Church.
We acknowledge one baptism for the remission of sins.
We await the resurrection of the dead and the life of the world to come.
The Orthodox Church is the original Church of Christ, founded by Christ himself. Over the past 1,000 years, other groups have severed themselves from the Orthodox roots that all Christians once shared, either by adding elements to the faith or eliminating them, but the Orthodox faith has remained unchanged since the beginning.
Orthodox believe that the Church is the living Body of Christ. It is through a life in the Church that we strive toward and ultimately attain union with Christ. The Orthodox life is a continual effort toward returning to the state in which we were prior to Adam’s fall from grace, and toward preparing ourselves for the blessed state in which we will be, if God allows, in eternity. Thus, the Orthodox life is both a holy struggle and a foretaste of heaven on earth. We consider sinfulness an illness, a spiritual condition that afflicts each of us, and we place emphasis on healing from that illness rather than on punishing ourselves for it. We believe that God is loving and merciful and desires to save us. We also believe that God does not force salvation upon anyone; in other words, we have to do our part.
We believe that our faith, not our obedience or good deeds, is what leads us toward salvation. At the same time, however, we also believe that obedience and good works are vital aspects of such faith. In other words, our works, our actions, our words, and our thoughts are all reflections of, and therefore evidence of, precisely what we believe or do not believe. We are all sinners, but Orthodox believe that we are called toward and capable of becoming righteous before God. What makes a person righteous is not privilege and not necessarily accomplishments; rather, it is the struggle toward holiness in the face of temptation — the choice to pick up one’s cross and carry it.
In Orthodoxy, there are constant reminders that we are never alone in that struggle. God helps us directly through the Divine Mysteries – what, in Western terms, we might call a “sacramental” life in the the Church – holy baptism, communion, confession, marriage, and so forth. We also have the spiritual assistance of Angels and Saints to guide and support us in our struggle toward spiritual transformation. In much of modern Christianity, turning to the heavens for intercessory prayer is a practice that has long been abandoned, perhaps even disparaged, but in Orthodoxy we consider it one of our greatest treasures. Each of us has a guardian angel to protect and help us. Each of us has a patron saint to pray on our behalf. Among Serbs, each of our families also has a patron saint to pray on our behalf. Indeed, we are not alone.
In addition to asking the Saints for their prayers, we also look to them as examples of sincere, Orthodox faith. In their earthly lives, the various Saints did not necessarily travel similar paths: Some were priests and bishops, while others were laity; Some were monastics, even hermits, and others were married with children; Some were renowned theological teachers or prolific writers, while others were completely illiterate; Some were of wealthy and even royal upbringing, and others were simple peasants; Some were prophets ordained by God, some were called to a life of the strictest asceticism from early in their youth, and yet others were great sinners who lived much of their lives in depravity; Some received crowns of martyrdom through gruesome torments, while others received their crowns by martyring their own wills through lifelong ascetic labors. What all of the Saints share in common, though, is their sincere and fervent faith in Christ. They do help us by praying for us, but they also help us by providing us examples to follow, as well as the inspiration and courage to seek and preserve the profound degree of faith that they maintained in the face of every conceivable type of earthly struggle.
Above all of the Saints and even the Angels, Orthodox believers venerate the Most-Holy Theotokos, or Mother of God. Human like us, yet completely pure and undefiled by sin, she is created, not divine, yet she is superior to all of creation — truly, more honorable than the Cherubim and more glorious than the Seraphim. Her holy womb contained that which the heavens are not wide enough to contain; therefore, her love as a mother is boundless. Many of the major feasts of the Church are dedicated to the Theotokos, and there are countless stories of wonderworking Holy Icons bearing her image that have worked miracles in the presence of those who believe.
Both iconography and icon veneration are central to Orthodox worship; our churches and homes are filled with images of the Theotokos, of Angels and Saints, and of course of Christ our God, and we greet them with a kiss before and after our prayers in much the same way that we might greet our loved ones with a kiss as we come and go. Contrary to what certain critics believe, we do not worship icons. We do not worship anyone or anything other than God, the Holy Trinity. However, we respect and reverence icons because we consider them windows to heaven. They are not merely pieces of wood with paint on them; they depict holiness and Truth. Practically every aspect of the painted icon is symbolic and tells a story, a piece of Christian theology. More importantly, though, icons help us to “see” heaven. They remind us that our prayers are being heard because they show us the faces of those who are listening.
Like many other aspects of Orthodox faith and practice, the use of iconography has its roots not only in Scripture but also in Holy Tradition. Many outside of Orthodoxy have attempted to erase even the slightest semblances of Tradition from their expressions of faith. Within Orthodoxy, however we take all of our spiritual directives from Tradition. Our great Serbian Saint Nikolaj (Velimirovic) describes Holy Tradition as the vast body of “spiritual treasures which we inherited from our holy ancestors, which are in absolute accord with the Holy Scriptures, and which help us to understand Holy Scripture rightly.” The Scriptures are indeed God’s revelation to us, and we are meant to be obedient to them, but Orthodoxy emphasizes the importance of understanding that revelation in its proper context so as not to misinterpret it. Many Christians today discount the authority of anything not explicitly stated in Scripture, but they do not realize that Scripture itself is but a single piece of Holy Tradition, which is older and much farther-reaching than Scripture is. In these very Scriptures themselves, the Apostle whom Jesus loved confirms that there is more to Christianity than the Bible: “And there were many others things which Jesus did, which, if they should be written, every one, I suppose that even the world itself could not contain the books that should be written” (John 21:25). 
In much the same way, it is difficult to encapsulate everything that Orthodox Christians believe into a single page on a website. The preceding words are not meant to introduce any complex matters of theology, nor should they be construed as the “most important” tenets of Orthodoxy. They are merely a glimpse into a few of the aspects of our faith that are outwardly observable and noticeably different from Western ideas. 
For more in-depth reading, you may find the following websites helpful.
Orthodox Church in America: Questions and Answers http://oca.org/questions 
Orthodox Info http://orthodoxinfo.com/ 
Preacher’s Institute http://preachersinstitute.com/ 
Saint Gregory Palamas Outreach http://www.saintgregoryoutreach.org/ 
Spiritual Nourishment for the Soul http://www.serfes.org/