The Jerusalem home of a prominent Israeli ethicist and atheist philosopher was vandalized overnight Wednesday in an apparent hate crime carried out by Jewish extremists.

Graffiti depicting a Star of David and references to biblical passages were sprayed on the fence around the house of Prof. Yaakov Malkin, director of Tmura, the International Institute for Humanistic Secular Judaism.

An envelope containing a threatening letter and a knife branded with a further biblical reference were also found at the scene, according to police.

Get The Times of Israel's Daily Edition by email and never miss our top stories Free Sign Up

Malkin, 89, is a well-known writer and educator, espousing an ethical and humanist approach to Judaism and religion. As well as serving as the academic director for Tmura, Malkin is the chief editor of Free Judaism, a journal for cultural Judaism, which he founded in 1995. He is the author of a number of influential atheist works including “Judaism Without God? Judaism as Culture and the Bible as Literature.”

The phrase “Destruction of Amalek” – a biblical commandment to wipe out the Amalekite nation, who attacked the Israelites on their way out of Egypt – was scrawled on a wall around Malkin’s home along with the biblical chapter and verse reference, “Exodus 16:14.” “Psalms 139:21-22” was written on an adjacent wall

The reference from Exodus seems to be a mistake, as the corresponding passage describes the manna given by God to feed the Israelites during their travels in the desert.

The graffiti is most likely referring to the same verse in chapter 17, which expounds on the edict to destroy the Amalekites.

The same mistaken passage reference was also written on the knife left outside the house. Police did not give details of the note found with the knife.

כך נראתה הבוקר הכניסה לביתו של פרופ' יעקב מלכין, ראש המכון ליהדות ישראלית חילונית pic.twitter.com/R8DJtuVXZh — רועי ינובסקי (@Roi_Yanovsky) January 21, 2016

The passage from Psalms reads, “Did I not hate Your enemies, O Lord? With those who rise up against You, I quarrel. I hate them with utmost hatred; they have become my enemies.”

An investigation has been opened into the incident.

On Saturday the Dormition Abbey in Jerusalem was vandalized with anti-Christian graffiti, the latest in a series of hate crimes against Christians and churches in Israel in recent years. Two people were arrested Wednesday in connection with that incident.