The word "Orthodoxy" comes from words "orthe" = correct and "doxa" = opinion, faith. So was the Apostolic Church named in contrast to the heresies. The Orthodox Church is keping the apostolic tradition unchanged, and whatever it believes in and declares is based only on Holy Scripture, which is the written part of tradition, and on unwritten tradition as well.
The Orthodox Church is the real and living body of Jesus Christ, strongly connected and united by the presence and actions of Holy Spirit, for Whom It believes that " It proceeds from the Father" (Jn 15:26), and continues endlessly (as long as there are humans willing to be saved) Christ's salutary acts. If someone wants to be saved and enter the Kingdom of the Heavens, has to take part in the salvatory events of Christ's life. He should die for sin, and be ressurected for a new life, the last step of which is unity with God.
To reach this goal, there are provided by God many ways for us to receive His Grace. These are the Sacraments or "Mysteries". Many have tried to number these Mysteria to seven. The truth is that almost every action of the Orthodox Church is a Mystery, meaning that it is an expression of the one and great Mystery of human salvation.
The relation of Orthodoxy and heresies (greek "Haireseis"= separated parties) is that of a tree and a broken branch. The broken branch is dead, while the tree continues living and growing. Someone is called a heretic when he has declined from orthodox faith, as expressed in Holy Scripture and the confessions of the Seven Ecumenical Councils, which have explained every topic of creed. The Holy Spirit DOES NOT operate outside the Orthodox Church (as He himself has so declared), so there is no salvation for heretics. That is easy for anybody to understand: how can they take part in the life of Christ, since they are cut off from His body?
Every human being can and should take the road of salvation. What does he have to do? "If any man would come after me, let him deny himself and take up his cross and follow me"(Mat 16:24) answers Jesus. A man's "self" whom he has to deny, is his old self, his bad habits and the inclination to sin which all humans have inherited from Adam's sin. As for a man's cross, Christ explains: "Take my yoke upon you,and learn from me; I am gentle and lowly in heart, and you will find rest for your souls. For my yoke is easy, and my burden is light."(Mat 11:29,30). So a Christian has to take up his burden; what is that? "If you were of the world, the world would love its own; but because you are not of the world, but I chose you out of the world, therefore the world hates you."(Jn 15:19). The conclusion is one: we have to leave this condemned world, so we can join freely the new, eternal world of God. "No one can serve two masters; for either he will hate the one and love the other, or he will be devoted to the one and despise the other. You cannot serve God and mammon."(Mt 6:24)
So an Orthodox has to live ascetically. That means that he has to exit the world, not in place but in mentality and in the way of living. There is nothing common between an Othodox Christian and an earthly man. In this sense there is not an essential difference between a layman and a monk. Besides, Monasticism was developed as a protest against the worldliness of the christianized masses. The Christian might live inside the world, but not "as the world".
The Church has no connection with this world. We don't deny its presence, but we do deny its ways. We don't expect to be saved in another world, but we strongly believe that this world will be saved and reformed. That process has already begun, with the presence of Christ and His Church in the world, and will be finally completed with the Second Presence of Jesus Christ, and the Judjement Day.