I pose this question since someone I know was received into the Orthodox Church (the communion to which I belong) by baptism, even though he had been baptized in the name of the Holy Trinity (Father, Son and Holy Ghost) as a Missouri Synod Lutheran. In the west, this question was pretty much settled after St. Augustine's efforts to deal with the Donatist controversy in a series of North African synods (a prime example of Orthodox ecclesiology at work, IMHO). In the Eastern Church, however, St. Augustine's authority is somewhat negligible, and some even denying him the status of sainthood (!).
It is obvious that the situation cannot long remain as it stands, with some bishops recieving converts by chrismation, and some by (re)baptism. To quote St. Augustine: "In the sacrament, two things are certain: God's grace in giving it, and my faith in receiving it. If you get in the way, then I have no way of knowing anything is certain."
I invite your comments. I will be moderating them, and ANY comment that's made uncharitably will be removed IMMEDIATELY. Please keep this discussion lively, but in a spirit of charity.