Kazimierz Lyszczynski (Polish pronunciation: [ka'?imj?? w??'t??j~sk?i]; 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 podsedek (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.