Exactly like Heorhij said, heterodoxy and heresy are indeed very different things, as we can't say RC's are heretic for something that was never condemned at an Ecumenical Council. Then why should we be worried of this? Because RC's call it a DOGMA. A dogma is something which must be absolutely believed by a person in order to be a Christian. RC's then, proclaiming IC as a dogma of the Church, are thus indicating that WE Orthodox Christians are heretic because we don't proclaim it (as well as other dogmata as Papal Infallibility). Then the problem isn't "Is the Immaculate Conception a possible belief for an Orthodox?" but "Should we accept a dogma of a separated ecclesiastical body who has got no power at all to proclaim universal doctrines?". Put in other words, a public and authoritative proclamation of this dogma by the Orthodox Church could even be to Roman Catholics as a sign that we are recognizing Papal Infallibility and the superiority of the Church of Rome on the Patriarchs and autocephalies of the Easter Orthodox Church!
That's why any Orthodox can have his own opinion on the subject and no Orthodox hierarch will ever impose IC, Augustinian "Original Sin" and other Latin doctrines on the faithful. After all, any theological opinion (theologumenon) on matters which were never defined has never been an occasion for excommunication to the same Augustine of Hippo, for example. The official doctrine on Immaculate Conception is nothing but another instrument to repeat that the Pope can say what we must believe, even contrarily to the consent of the bishops and Ecumenical Synods.
In Christ, Alex
That might be a good reasoning for Orthodox, but I'm affraid RC won't be impressed.
The problem with IC as I see it is underlying presumption about the necessity of Theotokos being conceived in any other fashion than us, other humans, and that's exactly because we inherited something (responsibility, guilt, whatever) from Adam's sin.
The underlying reason of Ephesus and Chalcedon was union of God and man in the person of Christ, and inseparability of that union as from His conception, through death and Resurrection until all ages. And we are separated from pre-Ephesians and pre-Chalcedonians for our perception of the consequences of their beliefs that might put that union under question mark.
IMHO, underlying logic of IC puts more severe question mark on that union, since it assumes it actually isn't possible, except in case of Theotokos, whom was conceived immaculately. If it was, why the need for IC?
Moreover, the reasons of inability of (the rest of ordinary conceived) humankind assume "God is angry at us, for Adam and Eve were naughty, and we are naughty" (copyright my RC sis when she was 7 o 8 ). If He wasn't angry and disgusted, why the need for IC?
Together with filioque, IC is the evidence that we should ask ourselves if RC still believe the same God as us.Fixed "8 )" to override automatic smiley -PtA