The first thing to clear away is the caricature. The Orthodox do not reject the Immaculate Conception because they hold a low view of Mary — their veneration is, if anything, more exuberant than the West’s. They call her Panagia, the All-Holy; achrantos, the spotless one; higher in honor than the cherubim. The dispute is not about her sanctity. It is about the machinery the 1854 dogma assumes.

Here their case is serious. The definition says Mary was preserved “from all stain of original sin” — in Pius IX’s own Latin, originalis culpae, original guilt. But the East does not hold that we inherit Adam’s guilt. It holds ancestral sin: from Adam we inherit mortality, corruption, and a disordered pull toward sin, but we are personally guilty only for our own sins. Remove inherited guilt and there is nothing for a “preservative exemption at the first instant” to do. As the Orthodox see it, the dogma is an answer to a Western question — a problem generated by Augustine’s juridical framework, not by the common apostolic faith. And it was defined by papal authority alone, apart from an ecumenical council, which the East cannot receive as binding however it might esteem the underlying piety.

The Catholic answer begins by reading the definition exactly. It is preservative redemption: Mary was preserved “in view of the merits of Jesus Christ, the Saviour of the human race.” She is not the one human being who needed no Redeemer; she is the first and most perfectly redeemed — saved more completely, not less. That answers the deepest Eastern worry, that the dogma would cut her off from the race she shares with her Son. And on the substance, the two lungs are close: the East already keeps the Feast of her Conception and sings of her purity from the womb. Catholics can grant the Eastern emphasis — mortality and corruption, not transmitted personal guilt — and still confess that from the first instant she was full of grace.

So the honest core of the disagreement is narrow, and worth stating without spin. The dogma is phrased in a Western, juridical register; the East’s complaint that it speaks a foreign dialect is fair on its face. Catholic tradition was itself divided before 1854 — St. Thomas Aquinas held that Mary was sanctified after her animation, not preserved in the very first instant, and the Dominican school resisted the doctrine for centuries. The blanket Orthodox “no” is partly a reaction to the papal definition; before it, as Kallistos Ware concedes, the question “belongs to the realm of theological opinion.” None of which makes the dogma negotiable for a Catholic: since 1854 it has been defined and is held de fide — what a Catholic may grant is the Western cast of its language, never the truth it defines. The deep agreement is on her holiness. The live difference is the framing — and the authority that made it dogma.