As someone who studied history I have to reply to this
Soyeong: Indiscriminate destruction of ancient literature by institutional Christianity never occurred;
This is simply not true. While a lot of roman and greek scripts survived since they had a special status with the Roman empire and so with the early church, most of the "foreign" literature, religious or not, was deliberately destroyed. Libraries were burned, temples destroyed.
Some of it may have survived in the vaults of the Vatican, but is inaccessible even today except to very highranking catholics.
Also with the spreading of the christian belief around the world vast amount of non-written literature (oral traditions) were suppressed and so willfully destroyed. Were it not for Iceland (were the ruler formally became christian to please the king in Norway while telling his people that at home they can do what they want) what we have of the Edda would only be a few fragments.
We have in central europe (from written accounts of christian monks) a lot of references to oral traditions of germanic and celtic origins but we have lost the "texts" since spreading them was heresy and dangerous and so the bards and skalds with them their most of the old stores simply died out.
Some of it transformed and survived in fairytales (as for instance later written down by the Grimm brothers - and they still had to change and censor the stories). Some was written down by monks that tried to preserve them, but they also changed parts, eradicated references to the old gods and heroes and included christian elements - heavy refactoring to a) bypass censorship and b) remake the old tales that were hard to root out with a christian flavour.
Soyeong: There was no attempt to suppress pagan writing per se;
That is not true. See the destruction of the oral traditions above. An early exception were the roman and greek writings since it was not possible to suppress them in the early christian roman empire since that would have been an affront to the educated and rich and would have led to a palace revolt.
Outside italy and greece "pagan" writings were heavily censored - just by the fact that the christian church held a monopoly on education and you had to be christian to become literate.
Soyeong: On a few occasions, pagan tracts specifically attacking Christianity were condemned but others have been preserved;
As I said, that is true only for roman and greek writings that were widely spread among the educated romans and greek nobles.
Soyeong: Suppression of heretical Christian writing was widespread;
That depends on the time. In the early days there was no "heretical" writing since there was no "official" canon. Over the course of some church convents the high priests decided that official canon - for instance which accounts on Jesus would be included into the "New Testament" and which would not. That was necessary since the accounts were in parts highly contradictive - ie. Jesus living happily thereafter here on earth and having a bunch of children with Maria Magdalena, and also - very importantly - different accounts on prophecies regarding the end of the world.
These different accounts on Jesus lead to numerous different sects of early christianity that threatened the power monopoly of the roman church and many of those sects were (quite naturally, since their followers were no jews) not very close to the Abrahamic god but incorporated Jesus into their own local/traditional pantheon.
So what christians believe today about Jesus was deliberately chosen from a range of accounts by a bunch of powerful people. They chose what suited them best and contradicted their intentions and in itself the least. Everything else was declared heresy and rooted out with (literally) fire and sword. Some of the early sects survived in secluded areas up until the late middle ages.
Soyeong: Magical and esoteric works were treated in exactly the same way as they were under the pagan Emperors, who had not been very sympathetic;
No. The Pax Romana stated that under roman rule people were free to practise their religios traditions - as long as they didn't threaten the said Pax Romana. That included of course a lot of magic practise - magic was closely intertwined with religions and medical care.
Black magic was of course forbidden - like harming other people, be it fraud, bodily harm or murder, is today.
Soyeong: With some exceptions, respect for pagan learning was widespread among Christians;
No, the other way round. With the exception of roman and greek writings everything else was deliberately destroyed. Even a lot of that is lost. Works of literature like Homers writing were allowed to survive since they were seen as that - literature, not religious texts. Also the works of the greek philosophers and roman scholars survived since they were studied by the roman elite.
Most of the real religious texts (As not dramatized like Homers writing) were rooted out.
Soyeong: The survival of the classical literature we have was almost entirely due to the efforts of Christian monks laboriously copying out texts by hand.
Yes and no. First of all, they copied only what they were allowed to copy. A lot of texts were destroyed or got lost because they were not deemed worthy preserving. Also a lot of rare texts got destroyed by accident like fire, when monasteries (that held a monopoly on certain scripts) burned down due to lightning or civil unrest.
Very often texts were deliberately changed when they were copied, ancient heroes and were replaced with christian saints, gods of old were demonized or replaced with the christian god.