(A cousin of mine recently gave me Stăniloae's The Experience of God: Orthodox Dogmatic Theology in Romanian. Though in English it is published in six volumes or so, in Romanian it was published in three. I only have the first three volumes in English, so from now on, until I get English copies, citations from later parts of the series will be first quoted in Romanian and translated by myself. Maybe in this way I can attract a Romanian readership. . .)
Stăniloae opens his discussion of the sacraments in this way:
Biserica ortodoxă socotește că mântuirea nu se finalizează în moartea lui Hristos pe cruce, ca echivalent juridic al jignirii ce a adus omenirea lui Dumnezeu, ci in unirea lui Hristos cel răstignit și înviat cu oamenii ce cred în El, pentru ca și ei să poată muri păcatului și învia. Consecvent cu aceasta, ea acordă Tainelor un loc de mare importanță în iconomia mântuirii ca mijloace prin care se înfăptuiește această unire a oamenilor cu Hristos.
The Orthodox church considers that salvation is not completed in Christ's death on the cross, as an adequate satisfaction of the dishonor which humanity had brought upon God, but rather in the union of the crucified and risen Christ with people who believe in Him, so that they too may be able to die to sin and rise again. As a consequence of this, it accords the Mysteries an important place in the economy of salvation as means by which this union of persons with Christ is accomplished (Dumitru Stăniloae, Teologia Dogmatică Ortodoxă vol. 5, p. 4).
Here we see one critical manner in which Orthodox theology differs from much Western theology. The Western conception of salvation as completed by Christ's death is positively extrinsic, it has to do with things "outside" the human person (viz., an unfavorable judicial relation to God, the threat of eternal punishment, etc.). The Eastern conception, on the other hand, has much more to do with the intrinsic being of human persons: through a real union with Christ, the human existence is fundamentally transformed so that the human person can experience victory of sin and death. It has to do with the condition of the existence of the human person in itself, human being in itself, and not merely relative to an external being.
Because this transformation has to be internalized by the human person in some way, we have a conception of the sacraments or Holy Mysteries as means of accomplishing this end. You can see, for instance, how you might motivate a "higher" view of Christ's presence in the Eucharist: a real, transforming union with Christ's glorified body is accomplished by taking in part of it through the Eucharist, which is his body and blood.
With this kind of narrative of salvation in mind, furthermore, we can see how we might understand Paul's discussion of baptism in Rom 6 or Gal 3 as a robust, real method of union with Christ.When he says, for instance, that all of us who were baptized into Christ Jesus were baptized into his death . . . we have been united with him in a death like his [so that] we will certainly also be united with him in a resurrection like his . . . we died with Christ (Rom 6.3, 5, 8). Or all of you who were baptized into Christ have clothed yourselves with Christ (Gal 3.27).
Recently on Facebook, I suggest that people do not have an appropriately robust understanding the role and essential function of baptism because they take an objective genitive reading of πίστις Χριστοῦ in Paul. If justification and the good stuff of salvation come through my faith in Christ, then it's not obvious why I have to be baptized. Why the urgency? Who cares? Let me put it off -- or not do it at all, as so many do.
But Douglas Campbell in The Deliverance of God, for instance, insists that Paul's gospel is fundamentally about Christ and what happened to him, before it is about us. "Justification" (Campbell interprets it as deliverance) is something that happened by Christ's faithfulness. For Campbell, Paul's gospel is that God has accomplished a deliverance of humanity in what happened to Christ at his death and resurrection, and we benefit from this only by participating in that reality. Apart from any such participation, there is no salvation.
I don't know if Orthodox theologians do any business with the πίστις Χριστοῦ debate, but I imagine they'd prefer a subjective genitive reading, if they find anything valuable in Campbell's picture of things. Stăniloae in the citation above gives the basic picture of salvation on the Orthodox scheme of things as participation in Christ, even though he would not use that language. Certainly his Christocentric reinterpretation of Paul's gospel lends itself to a more robust sacramentology as found in the Orthodox church.