I think a wrong emphasis is being placed on the immersion/pouring debate.
What is best said, I think, is that Orthodoxy has a problem with any sort of "minimalism" or attempt to discern what's the least we (or the Church Herself) can "get away with" when it comes to the salvation of souls.
Liturgically, post-schism Roman Christianity has been doing precisely the opposite - forever widdling down liturgical services, trying to divine just what is the "least" they can get away with doing, in order to keep everything "valid"...even when an obvious consequence of such a quest, is to diminish the clarity of the Christian Revelation.
This is the real problem with the latter day Latin pratice of considering "baptism by pouring" a normal means of receiving people into their church. It is also at least part of the problem, with the only recently modified Latin practice of only giving communion "under one species" during their Mass. Even their own "Catechism of the Catholic Church" recognizes this (at least to an extent), by saying that the practice of "batism by immersion" and giving communion "under both kinds" better expreses what these sacraments are supposed to be about.
The practice of Baptizing someone by pouring water over their head, as ancient documents like the Didache make clear, was never considered the ideal, but a contingency when the necessity arose...for example, if there was some real scarcity of water, or if someone had become so feeble that immersing them might kill them or adversly harm their health.
But there is a big problem with making rules out of exceptions... they are exceptions, precisely because they're supposed to be exceptional. As such, to make them "the norm" cannot but cause certain goods only conveyed by "the norm" to be lost in the process.
For while it is true the symbolism of the Holy Trinity, and to a degree, "washing" is maintained by "baptism by pouring", look how much is lost! The Scriptures tell us that spiritually, Baptism causes buriel with Christ, the death of the old man - can pouring a little water on someone's forehead convey this? The same Holy Scriptures say that Baptism is a new birth, a spiritual birth, with a similtude to our birth from the womb - can simply putting three little aspersions of water on someone's head convey this in sign? And while Baptism is ultimatly not the phsyical washing of a man, what better symbolizes the complete interior washing that is occuring - a little water over one part of a man, or his being totally plunged into water?
So you see, much is lost, when this practice is resorted to. Thus it is incredible, that a genuine "Church" would choose to make this the norm. Only a spirit of hyper-minimalism, could even begin to make the introduction of such a practice the norm.
Of course, all of this is to some extent secondary, to the more basic problem of heterodox baptisms, when taken on their own merit.
What should also be kept in mind, is the truth that historically, the Orthodox Church has accepted, via economy, converts from Roman Catholicism, Anglicanism, and other western schisms, who were undoubtedly "baptized" in their former religions by "pouring." The late heiromonk, Fr.Seraphim Rose (whose pastors in Christ were certainly not ecumenists; his reception into Orthodoxy was, in fact, ultimatly under the care of St.John (Maximovitch)) was a relatively modern example of this.
Seraphim
