How does Voltaire portray El Dorado, how does it differ from eighteenth-century Europe, and what are the religious beliefs of the people?

El Dorado, in Voltaire's famous Candide, is the legendary shining city of splendor. When Candide and Cacambo accidentally stumble into this magnificent city in the middle of their journeys, they are in for a surprise. Voltaire clearly uses it as a foil for his interpretation of eighteenth-century Europe: he has nothing but good things to say about El Dorado, while he couldn't be more disparaging toward Europe.
The city of El Dorado is a utopia of pristine perfection—the city's streets are lined with precious stones, the people are all rational and intelligent (the one place in this book where this is true), and everything the king says is humorous and intelligent. Additionally, there are no priests. This last bit is a personal token of Voltaire's utopia, stemming from his strong anti-religious sentiment.
Voltaire's view of Europe is very poor and is a clear contrast to this shining city. He believes the citizens of the continent are dumb, lazy, and irrational, as evidenced by the many other locations Candide visits in the story. Candide encounters cannibal and irrational Jesuits, is conscripted into an army under false pretenses, and sees monkeys who are the lovers of women. All of this is an examination of Voltaire's view of the continent, where he believes people are barbaric (like those cannibals and monkeys), driven by lust, and controlled by religion.
In contrast, the city of El Dorado is an atheist city—it represents the achievements of rational and scientific man, which Voltaire believes is above all else. With the absence of priests, the city is void of Catholicism and Christianity in general, which Voltaire believes would cause everyone to become rational, intelligent, humorous, and wealthy. Voltaire attempts to criticize Christianity in this section by showing the optimism and rationality that atheism and philosophy bring.