Question
Why was the sentence “She-hem mishtachavim…” deleted from the Aleinu prayer?
Answer
The historians tell us that the phrase was deleted under repeated pressure from Christian censors during the 14th to 17th centuries. The connection (by Gematria) to Christianity is in fact mentioned in the commentary Arugas Ha-Bosem, written in the 1200’s. For more details see the article on “Aleinu” in the Encyclopedia Judaica, vol. 2 cols. 555-559.