Kazimierz Łyszczyński (; 4 March 1634 – 30 March 1689), also known in English as Casimir Liszinski, was a Polish nobleman, philosopher, and soldier in the ranks of the Sapieha family, who was accused, tried, and executed for atheism in 1689. For eight years he studied philosophy as a Jesuit and then became a podsędek (supply judge) in legal cases against the Jesuits concerning estates. He wrote a treatise entitled On the non-existence of God and was later executed on charges of atheism. His trial has been criticised and is seen as a case of legalised religious murder in Poland. Life Education and work Kazimierz Łyszczyński was born in Łyszczyce, in what is now Brest District, Brest Region, Belarus. He became a nobleman, landowner, philosopher, and soldier in the service of the Sapieha family. For eight years he studied philosophy as a Jesuit, but left the order and then became a supply judge (podsędek) in legal cases against the Jesuits concerning estates. He was also member of the Sejm of the Polish–Lithuanian Commonwealth. Łyszczyński had read a book by Henry Aldsted entitled Theologia Naturalis, which attempted to prove the existence of divinity. But its arguments were so confused that Łyszczyński was able to infer many contradictions. Ridiculing Aldsted, Łyszczyński wrote in the book's margins the words "ergo non-est Deus" ("therefore God does not exist"). This was discovered by one of Łyszczyński's debtors, Jan Kazimierz Brzoska, who was the nuncio of Brest in Poland or a Stolnik of Bracławice or Łowczy of Brześć. Brzoska, reluctant to return a great sum of money lent him by Łyszczyński, accused the latter of being an atheist and gave the aforementioned work as evidence to Witwicki, bishop of Poznań. Brzoska also stole and delivered to the court a handwritten copy of De non-existentia Dei, which was the first Polish philosophical treatise presenting reality from an atheistic perspective, and which Łyszczyński had been working on since 1674. Trial Witwicki along with Załuski, bishop of Kiev, took up this case with zeal. King John III Sobieski attempted to help Łyszczyński by ordering that he should be judged at Vilnius, but this could not save Łyszczyński from the clergy. Łyszczyński's first privilege as a Polish noble, that he could not be imprisoned before his condemnation, was violated. The Łyszczyński case was brought before the diet of 1689 where he was accused of having denied the existence of God