Kiss of death

This is something or someone that ultimately brings disaster or dysfunction to any endeavour. It is thought to derive from the most infamous kiss of death of all, the identification and betrayal of Jesus by Judas Iscariot: Luke 22:48, “Judas, do you betray the Son of Man with a kiss?” Even so, its current figurative use is only attested from about 1940. Perhaps in earlier times it was regarded as disrespectful or even blasphemous to use the phrase figuratively or trivially.