Thank you Kolo! Which actually brings up another point.
The author has a curious position that the fact of the Assumption is spurious, based on the Decretum Gelasianum (ca. 490s) which condemned the Transitus Mariae as heretical. I looked it up (see the link) and indeed, no question about it, the Transitus Mariae fell under the label of books that are not received by Catholics and should be avoided under anathema.
YET...the liturgical feast of the Assumption is at least this old. The Life of St. Theodosius states that the Church of Jerusalem celebrated a feast of the Assumption before A.D. 500. (I'll try to find this primary source as well)
Analog, I think you said you're an Anglican, so you understand feast days. Now how is it that we have a condemnation of the Transitus Mariae at around the same exact time that the Church in Jerusalem is celebrating its feast day?
Well, the easiest explanation I can think of is that the BOOK was condemned but the IDEA was not. One could argue I suppose that, well, maybe the Jerusalem Church was outside of the mainstream here, and they were sorta being corrected by the Gelasian Decretals. But I don't think that flies, because as Kolokotronis said, the feast wasn't squelched but kept going. It was present in the Greek liturgy by the next century, and it appears in the Roman "Gelasian Sacramentary" (!), the dating of which is problematic.
Evidently, the condemnation of the book had no effect on the spread of the feast or of the theology of the idea. Which, again, indicates to me that we are dealing here with a tradition of the Church which was *not* heretical, but which was orthodox.
The dogmatic declaration of the Assumption from 1952 of course is very, very recent and as we know is silent on whether or not Panagia actually died before she was assumed bodily into heaven.
Readers here who don’t already know should understand that the entire Church, East and West, for 1400 odd years at least celebrated the “Dormition”, the “Falling Asleep” or death of the Theotokos. It was in the West and still is in the East, “theologoumennon”, a pious belief not necessary for salvation, that she was bodily assumed into heaven. In other words, one could be a Latin until 1952 and one can still be Orthodox and NOT believe that Panagia was bodily assumed. I will add however that I have never met any orthodox Christian who didn’t believe in the Assumption or that she actually died.