Question: Can a newborn baby make the decision to repent of his Adamic nature and become born again?
"Question: Can a newborn baby make the decision to repent of his Adamic nature and become born again?
Your question is really two and I suspect you know the answer to the first. Nevertheless....
Clearly a newborn baby can't make much of any decision about anything, much less about repenting. But what has this newborn to repent of; guilt of the Sin of Adam? I am assuming that's what you mean by "his Adamic nature". Orthodoxy does not hold by the post Reformation innovative notion which has developed over the past 500 years that we are in any way "guilty" for Adam's Sin. As for being "born again", well I have no doubt that a baby doesn't have the capacity to make that decision either. That baby, however, as far as The Church is concerned, is indeed "born again" by baptism by being received into The Church and thus worthy to receive and act upon God's grace and become "like God", to experience that theosis which was God's purpose for Creation in the the first place, the possibility of attaining which Creation lost through the Sin of Adam and which was restored to us by the mystery of the Incarnation. "God became man so that man might become like God", say +Athanasius the Great.
Here's a link to the Greek Orthodox Archdiocese page on infant baptism: http://www.goarch.org/en/ourfaith/articles/article7067.asp