Mysteries: Gateways into the Kingdom
The Mysteries, sometimes called "Sacraments" in the West, are the central part of an Orthodox Christian's life. They bring us into direct contact with God through being part of His Body. Christ being God and Man, the Mysteries are those direct and indirect points in the life of a Christian where the wall between God and Man have become destroyed. Prayer is, in some way, linked to the Mystery: during the Mystery, God responds. This Divine/Human union is a reflection of the nature of Christ Himself.
The Mysteries are the perfection of the Law: they are beyond and outside of her, and they are the perfect fulfillment of the Law. In this sense, they are all linked directly to the power of Christ's Death and Resurrection, which is, itself, the ultimate Mystery.
The choice of the word "Mystery" to describe these Divine and human interactions is important for a number of reasons, the first being that we don't really understand how a Mystery works (hence, they are "mysteries"). In the West after the great schism, the Mysteries became viewed a sort of mechanical action on the part of the church for the sake of our salvation, which the Protestant Reformers rightly began to deride as a mechanical formula. As well, stupid questions began to arise as to which "Church prayers" are "sacraments", and which ones create "sacramentals", or effects of the sacraments or "sacrament-like prayers". This incredibly ridiculous mode of thinking forgets the central part of the Mystery: the Church is the Body of Christ!
In a sense, to an Orthodox Christian, everything good after the Mystery of Baptism can become, in some way, united to Christ. This is why we bless our food, why we bless our families, why we bless our homes.
St John of Damascus, one of the greatest teachers of his age, writes this concerning the Holy Mysteries:
Man, however, being endowed with reason and free will, received the power of continuous union with God through his own choice, if indeed he should abide in goodness, that is in obedience to his Maker. Since, however, he transgressed the command of his Creator and became liable to death and corruption, the Creator and Maker of our race, because of His bowels of compassion, took on our likeness, becoming man in all things but without sin, and was united to our nature. For since He bestowed on us His own image and His own spirit and we did not keep them safe, He took Himself a share in our poor and weak nature, in order that He might cleanse us and make us incorruptible, and establish us once more as partakers of His divinity. For it was fitting that not only the first-fruits of our nature should partake in the higher good but every man who wished it, and that a second birth should take place and that the nourishment should be new and suitable to the birth and thus the measure of perfection be attained. Through His birth, that is, His incarnation, and baptism and passion and resurrection, He delivered our nature from the sin of our first parent and death and corruption, and became the first-fruits of the resurrection, and made Himself the way and image and pattern, in order that we, too, following in His footsteps, may become by adoption what He is Himself by nature, sons and heirs of God and joint heirs with Him. (An Exact Exposition of the Orthodox Faith, IV.xiii.)
Thus, if we look to the meaning of the Mysteries with post-Christian, post-modern eyes, we will demand categorization. This is a mistake. We need to see the Mysteries in the sense of our life in Christ and in the sense of the people he preached to, and those who received His Word, and in the sense of Christians being in the world, but not of it. Outside of this mindset they will make little sense. The mysteries are not signs, they are not testimonies, they are not magical actions that give grace but the Living presence of the Holy Spirit moving through out the Church, a mighty wind that began on Pentecost.
The Temple and the Mysteries
The typical Church building in Orthodox Christianity has always been called the Temple, thus perfecting the old Temple. The Church is the community, not the building. This confusion in English usage has rightly led to many non-Orthodox condemning the idea of having a building, lest it replace the thought of the Church as the Body of Christ. A Temple is a building, and in our day, many are constructed in people's homes (albeit temporarily).
The Temple rites and prayers that were found in the Old Testament are perfected in the New. The sacrifice of animals has been replaced by the perfect sacrifice of Christ which suffices for all mankind. Certain Mysteries take the place of the Old Law, and in this sense have a limited value. We can briefly the most prominent of these here, bearing in mind that the Mystery is something beyond our categorization, and that these Mysteries are only a part of the great Mystery that is Life in Christ.
The Mystery of Baptism and Holy Chrism: The Entry into the Temple
Holy Baptism is the central moment of change in a Christian's life; he is separated from the world and united to Christ. The addition of Holy Chrism to a baptized person was a confirmation of the person's standing in the Church; the Baptism becomes, as it were, sealed with the Holy Spirit, as the text of the Mystery itself states.
In our post-Christian understanding, the Mystery of Baptism has become understood to be two Mysteries that work apart from each other. This notion developed through historical circumstance, but it is a misunderstanding. In the West, the Bishop, being the successor to the Apostles, applied the chrism after the priest performed the Baptism. In the East, the Bishop authorized the priest to carry the chrism himself as his representative. Both came from a perfectly normal understanding of Baptism, but the historical growth of Christianity in the West led to the problem of the Bishop being present at every Baptism. Thus, the Bishops came once a year during pastoral visits to complete the Baptisms. This led to an understanding of chrismation apart from Baptism, when in reality the chrism was actually the sealing of the Baptism itself. It is a "double sacrament", or sealing, in the words of the Church Fathers.
Baptism is commanded in the Holy Scripture:
Jesus answered, and said to him: Amen, amen I say to thee, unless a man be born again, he cannot see the kingdom of God.
Nicodemus saith to him: How can a man be born when he is old? can he enter a second time into his mother's womb, and be born again?
Jesus answered: Amen, amen I say to thee, unless a man be born again of water and the Holy Ghost, he cannot enter into the kingdom of God. That which is born of the flesh, is flesh; and that which is born of the Spirit, is spirit. Wonder not, that I said to thee, you must be born again. (Jn 3:3-7)
The Mystery of the Eucharist: Partaking of the Sacrifice
St John of Damascus writes this concerning the Holy Eucharist:
For when He was about to take on Himself a voluntary death for our sakes, on the night on which He gave Himself up, He laid a new covenant on His holy disciples and apostles, and through them on all who believe on Him...having broken bread He gave it to them saying, Take, eat, this is My body broken for you for the remission of sins. Likewise also He took the cup of wine and water and gave it to them saying, Drink ye all of it: for this is My blood, the blood of the New Testament which is shed for you for the remission of sins. This do ye in remembrance of Me. For as often as ye eat this bread and drink this cup, ye do shew the death of the Son of man and confess His resurrection until He come....And now you ask, how the bread became Christ’s body and the wine and water Christ’s blood. And I say unto thee, “The Holy Spirit is present and does those things which surpass reason and thought.” Further, bread and wine are employed: for God knoweth man’s infirmity: for in general man turns away discontentedly from what is not well-worn by custom: and so with His usual indulgence He performs His supernatural works through familiar objects....But if you enquire how this happens, it is enough for you to learn that it was through the Holy Spirit, just as the Lord took on Himself flesh that subsisted in Him and was born of the holy Mother of God through the Spirit. And we know nothing further save that the Word of God is true and energises and is omnipotent, but the manner of this cannot be searched out. (An Exact Exposition of the Orthodox Faith, III.xiii)
The Scriptures on this are extremely useful for understanding.
Then Jesus said to them: Amen, amen I say unto you: Except you eat the flesh of the Son of man, and drink his blood, you shall not have life in you. He that eateth my flesh, and drinketh my blood, hath everlasting life: and I will raise him up in the last day. For my flesh is meat indeed: and my blood is drink indeed. He that eateth my flesh, and drinketh my blood, abideth in me, and I in him. As the living Father hath sent me, and I live by the Father; so he that eateth me, the same also shall live by me. (Jn 6:54-58)
The word used for "eat" in Jn 6:54 is actually a verb used for animal eating, "munch" or "gnaw", et cetera-- and is said by Our Lord to increase emphasis on the need to eat His flesh. This was so strong a doctrine of the early Church that the Roman Empire in which they lived made martyrs out of many Christians on the charge of cannibalism, mistakenly assuming that they were eating random body parts of Jesus like His hands or feet.
The two mysteries above (Baptism and the Eucharist) are the central aspects of the life of an Orthodox Christian. Baptism opens the door through which one enters the Church. The Eucharist, the "medicine of immortality", gives life to the Christian to continue his days. Other mysteries, each a revelation of the Divine but less visibly than the mystery of the Eucharist are listed below. There is no precise list to work with on precisely what a mystery is, though attempts have been made through the Church's history.
The Orthodox Church teaches that when one falls through sin after baptism, he can be healed through the confession of his sins, and the prayer of the Church restores him to communion with Her. This is done through the mystery of repentance, or confession and is either done before a priest of the Church, or the entire community (the latter being considerably less popular for obvious reasons.) As well, the Church uses holy oil to anoint those who are sick for the healing of their illnesses. The other mysteries are mysteries which seal the identity of the believer in question and include ordination to the priesthood, marriage (some also include monastic tonsuring, and this makes sense in terms of a sort of marriage parallel).
Life in Christ as a Mystery
In the end, life in Christ is itself a part of the life of the Mystery of the God-Man, Jesus Christ. In the Orthodox Church, virtually everything in a Christian's life is blessed in a tangible manner, from the food we eat (meal blessings) to the cars we drive (any object we use in everyday life can be blessed by the Church) to the water we sprinkle and bless the walls of our homes with (done once a year on the feast of the Theophany). Through the Incarnation, creation is renewed and death is defeated. The Holy Mysteries are the way we participate directly in the process of uniting to God our Father and live our lives as restored children of God, having lost communion with Him through Adam's sin, and having regained it in Christ.