If Father Ramon Ruiz-Sanchez's crisis on Lithia—debating whether an apparently virtuous alien culture might be a temptation or a truth—hooked you, you'll be riveted by Jesuit linguist Emilio Sandoz's mission to Rakhat in The Sparrow. As with Ruiz-Sanchez's plea to quarantine—or even "exorcise"—an entire planet, Sandoz faces miracles that curdle into moral catastrophe. Where Egtverchi’s arrival on Earth exposes human society’s fault lines, Sandoz’s return forces a reckoning with faith, guilt, and what it costs to truly meet the Other.

If you were drawn to the way A Case of Conscience turns Ruiz-Sanchez’s scientific training and theology into a maze of unanswerable questions, Lem’s Solaris pushes that tension to the brink. Psychologist Kris Kelvin confronts a sentient ocean that mirrors his psyche, much as the Lithians forced Ruiz-Sanchez to ask whether morality can exist without God. Like the Earth section with Egtverchi—where every attempt at interpretation spins society out—Kelvin’s station becomes a laboratory of doubt, grief, and epistemological limits.

If exploring Lithia’s serene, rational culture and its implications for human belief pulled you in, Le Guin’s The Left Hand of Darkness offers a similarly rich immersion. As Genly Ai navigates Gethen’s ambisexual biology, Karhide–Orgoreyn politics, and the fragile trust with Estraven, you’ll find the same careful, culture-first worldbuilding that made Ruiz-Sanchez’s debates over Lithian ethics so absorbing—minus the demonology, but with equally profound consequences for understanding the alien on its own terms.

If the non-technical, ideas-forward approach of A Case of Conscience—from Ruiz-Sanchez’s Jesuit biology to the cultural shockwaves of Egtverchi’s celebrity—was your sweet spot, Embassytown doubles down on soft-SF inquiry. Avice Benner Cho’s world is bound by the Ariekei’s untranslatable Language and human Ambassadors who speak with two mouths. As on Earth with the Lithian child, a well-intended human innovation destabilizes an entire society, forcing hard choices about meaning, truth, and coexistence.

If Ruiz-Sanchez’s recommendation to wall off Lithia—and the chaos after Egtverchi’s arrival—made you think about the ethics of contact, The Word for World Is Forest confronts colonialism head-on. On Athshe, human exploitation collides with a native culture’s values, provoking Selver’s transformation and a revolt against Davidson’s brutality. Where Blish frames a theological quarantine, Le Guin shows what happens when that boundary fails and power imbalances turn contact into catastrophe.