The issue of whether to baptize converts from other Christian confession or to receive them through some other means has its roots early on. It began while Christianity was yet illegal in exchanges between Pope St. Stephen of Rome and St. Cyprian of Carthage (both canonized saints) and never has received consensus within the entire Orthodox world. Most Orthodox who delve into the issue (which, of course, I cannot resolve here) cite the first Ecumenical Council, wherein the issue at hand had to do with triple-immersion baptism versus those done with a single immersion.
There were, at the time of the Council, certain heretics who baptized with one immersion that, upon being reconciled to the Church, were received via baptism, as their baptism was not according to the triple-immersion standard of the Church (and, incidentally, reflected a heretical theology). Those who baptized with triple-immersion were received via chrismation, regardless of their heretical theology (i.e., Arians were received via chrismation).
The issue in those days was one of making sure that form and belief were both present in the lives of those received; the former had to be given if such form did not exist prior to membership in the Church, while the latter could be corrected via chrismation and repudiation of heretical belief and confession of Orthodox doctrine (or, if chrismation had already been done in the previous confession, mere confession was done). The end result was supposed to be that all would eventually be baptized in the proper form and (ideally) hold the right belief.
Today this is more an issue of exactly into what or (in our case) into Whom we seek to baptize those coming into the Orthodox Church.
There are some -- the Baptists, for example -- who baptize with single immersion because, as they say, the Lord was buried once, not thrice, and we are baptized into his death, as St. Paul says (though, strangely to me, they deny that baptism is itself the moment wherein this baptism into His death is accomplished, in spite of their insistence that the rite reflect this very truth). So the objective, for them, is to reflect the burial and resurrection of our Lord as the already-finished τελος, or goal, towards which the baptism retroactively points.
The Orthodox would say that, though we are, indeed, baptized into His death, we are thus baptized so as to participate in the life of the undivided Trinity, hence our insistence on triple immersion. Three dunks, one baptism = Three persons, one Godhead. It is into this that we are ultimately baptized, and such a form reflects the much-developed trinitarian theology of the Church.
It used to be that the OCA had the following guidelines (citation HERE, emph. mine):
- Those converting from Judaism, paganism, and Islam, as well as those who distort or do not accept the dogma of the Holy Trinity, or where the baptism is performed by a single immersion, by means of baptism.
- Those whose baptism was valid but who either do not have sacrament of chrismation or who lack a hierarchy with apostolic succession (or if it is questionable), by means of chrismation. This group includes Lutherans, Calvinists and Episcopalians (Anglicans).
- Those whose hierarchy has apostolic succession and whose baptism and chrismation (or confirmation) was performed in their church, by means of repentance and repudiation of heresy, following instruction in Orthodoxy. This group includes persons of the Roman Catholic and Armenian confessions. If it happens that they were not chrismated or confirmed in their churches or if there is any question about this, they are anointed with the Holy Chrism.
One wishes, at this point, that we could all simply stop at "I acknowledge one baptism for the remission of sins" in our mutually-beloved Creed, no?