All 9 Uses of

heathen
in
The Magic Mountain

Granted, there was no sufficient reason for this sympathy—particularly if one disregarded such things as his heathen name, his status as a model pupil (which, indeed, could have played no role whatever), or those Kirghiz eyes, which from time to time, in certain sidelong glances, when gazing at nothing in particular, could darken, almost melt, to a veiled dusky look—but whatever the reason, Hans Castorp did not worry about the intellectual or emotional basis of his reaction, or even what name he would give it if he had to.†
Chpt 4.5

heathen = someone who is not civilized or not moral OR an offensive term for a person who does not believe in a preferred religion

Or, conversely, your Renaissance astronomers discovered the truth, and the cosmos is infinite, which means there is no world that transcends the senses, no dualism; the world beyond is absorbed into this world, the polarity of God and nature is annulled, and since the human personality is no longer the battlefield of two hostile principles, but rather harmonious and unified, all human conflict stems from the clash between the interests of the individual and of society as a whole, and so the purpose of the state become the law of morality, just as in good old heathen days.†
Chpt 6.3

His papal claim to temporal authority was not made for its own sake; proxy dictatorship was, rather, a means, a path to a redemptive goal, a transitional phase from the heathen state to the kingdom of heaven.†
Chpt 6.3

It corrects your heathen state morality with a little Christianity, a little 'individual rights,' a little so-called freedom, that is all.†
Chpt 6.3 *

His hands now loosened, parted, were spread and raised, palms outward, as if in heathen prayer.†
Chpt 7.3

In short, it was a true regaling cordial, a splendid drink that invigorated, stimulated, and quickened the system—an intoxicating drug, as well, by the way; one could very easily get a little tipsy and mellow from it, he said, gesturing with both fingers and head as he had the night before in the grand jocular fashion that made him resemble a dancing heathen priest.†
Chpt 7.4

The tilt of the head suddenly implied roguishness; the lips, still open, smiled lewdly; the sybaritic dimple, familiar from earlier occasions, appeared in one cheek—and there was the dancing heathen priest, who jerked his head in jest and pointed in a cerebral direction.†
Chpt 7.4

And then they saw that luxurious little dimple blossom—sybaritic roguishness, a dancing hitch of the robes, the holy lewdness of the heathen priest.†
Chpt 7.5

Definitions:

(1) (heathen)
someone who is not civilized or not moral -- typically said humorously

or:

an offensive term for a person who does not believe in a preferred religion -- especially someone who grew up in a culture that is not familiar with the religion
(2) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

More rarely, heathen can refer to a person who lacks culture or good taste.