Protestantism are not churches they are heresies and are cast off from the vine (or should we say there mother the RC was). The branch theory is heresy and what the said bishop of the OP claimed fits the bill. Any departure from Orthodoxy withers and dies. The entire tree is the One Holy Catholic and Apostolic Church which is the Orthodox Church and there is only a falling away from that tree, a cutting off (anathemas).
That's what I love about Orthodoxy. It's roots go all the way back to the beginning.