The divergence in practice regarding the form for reception of converts, like so much in our church life is due to history. The ancient canons provided for two options. Those of the heterodox who wished to convert were to be received by Chrismation, if the group they were converting from had maintained a belief in the Holy Trinity and in the incarnation of the Theanthropos. Those who were converting from other heterodox or schismatic groups were to be received by baptism, their prior baptism being considered null. This practice is still generally followed by the Ecumenical Patriarchate, the Church of Greece and the Antiochian Patriarchate.
Later in Russia, however, during the reign of Tsar Peter the Great, this rule was modified in the civil legislation that governed the church after the abolition of the Russian Patriarchate (i.e. during the Synodal period). This legislation, the Church Regulation (Tserkovniy Regimyent) provided a series of methods of conversion tailored to differing Christian confessions. Eastern Rite Catholics were received simply through sacramental confession and communion. Roman Catholics were received through a Confession of Faith, absolution and communion. Most Protestants were received through a Confession of Faith, absolution, Chrismation and communion. The specific Confession of Faith required of each group was tailored to its particular divergence from Orthodox theology. Muslims and Jews were, of course, received through baptism. This regualtion is, as far as I know, still operative within the Moscow Patriarchate; but is currently being reconsidered, as noted in a previous post.
The provisions of the Tservkovniy Regimyent were observed throughout the Russian church, including all the émigré churches, until the 1960's. Beginning in the 1970's the OCA began to follow the ancient canons, under the influence of Frs. Schmemman and Meyendorff, who were Byzantine scholars. At about he same time, under influence of the Holy Trinity Monastery in Brookline, the ROCOR began to receive all its converts through baptism. This practice went so far, that in the late 1970’ or perhaps early 1980’s a convert parish of former Episcopalians who had been chrismated by the Antiochian Archdiocese were received into the ROCOR and re-baptized, and their priest re-ordained. More recently, the monks of an OCA Monastery went to Mt. Athos where they, too, were re-baptized, to the chagrin of their diocesan bishop, Archbishop Dmitri of Dallas. That community is now part of the Jerusalem Patriarchate.
One of the arguments for re-baptizing all converts is that the various Protestant churches appear to have rapidly evolving theological standards, and it is no longer possible to determine with certainty, whether they indeed do uphold the belief in the Holy Trinity and the Incarnation.
The problem with the changing standards for receiving converts is that it has created confusion about the validity of prior conversions. Here in Oklahoma, one of the ROCOR priests has had to repeatedly defend the validity of his Orthodox identity and his priesthood from other members of the ROCOR because he was received from the Roman Catholic Church through Chrismation back in the 1970’s.
The fact that the OCA has no standard practice is unfortunate; but understandable given the general drift and confusion over recent decades. Sadly, the intellectual weight of the OCA’s founders was not carried on after the first generation, and some of the
OCA’s hierarchs have not had a sound theological education to inform their opinions about various subjects.
There is also a sort of posturing behind a lot of this. Currently, it is very fashionable in certain circles to appear a “traditionalist”, with a trailing beard, maximalist liturgical practices, extreme strictness in various observances, and an artificial nostalgia for some “pure Orthodoxy” of the past.