4 ideas
Father Ramon Ruiz-Sanchez, a Jesuit biologist, sits on a four-man commission deciding whether the planet Lithia should be opened to Earth. He finds that its reptilian inhabitants live by pure reason, with no religion, no crime, and flawless ethics. He votes to quarantine the planet because he believes it is a trap set by the devil, while the physicist Cleaver wants it sealed off as a lithium source for thermonuclear weapons.
To explain the Lithians, Ruiz-Sanchez concludes that Satan fabricated a whole world of virtuous creatures to show that morality needs no God. In Catholic doctrine only God can create, so granting the devil creative power is the Manichaean heresy. His defense of the faith against the evidence therefore forces him into a position the Church condemns, and he faces discipline from Rome.
The Lithian Chtexa gives Ruiz-Sanchez a sealed jar holding a Lithian embryo. It hatches and grows up on Earth as Egtverchi, without the environment that forms Lithians. He becomes a cynical television demagogue who incites riots in Earth's bunker-bound society, which suggests the Lithians' 'innate' morality depended on their world and upbringing rather than their nature.
The book never says which caused the destruction. The same event confirms either the religious or the scientific worldview depending on what the observer already believes.