Green’s Dictionary of Slang

(orig. US) a euph. for Jesus Christ!

1883		Daily Globe (St Paul, Minn) 30 Dec. 6/6: ‘Judas Priest’ or ‘Jujube Paste’ is the worst oath Gen. Grant ever swears.
1885		Courier-Journal (Louisville, KY) 1 Aug. 4/3: Men can not be great in all things. Gen. Grant was a poor swearer. His two most violent oaths were ‘Judas priest’ and ‘dog gone it’.
1890		Wichita Daily Eagle (KS) 21 Sept. 12/1: Judas H. Priest! Before I could say ‘scat [...] here come letters by the dozen.
1898		Salt Lake Herald (UT) 26 Apr. 4/5: The grand stand loudly murmers; the kids yell ‘Judas Priest!’.
1901		Ariz. Republican (Phoenix, AZ) 12 Mar. 5/3: This street is no place for us to fight, but by Judas Priest, Ill meet you tomorrow in the assembly chamber.
1909		Sun (NY) 18 July 29/1: ‘By Judas!’ he continued, ‘mebby that’s what’s the matter with them yaps’.
1910		University Missourian (Columbia, MO) 26 Aug. 4/5: ‘Pa, what’s a jeu-d’esprit?’ ‘Som thing that most people think they are saying when they exclaim "Judas Priest!"’.
1916		P. Kyne Cappy Ricks 279: Oh, by Judas priest, that’s right.
1925		Dos Passos Manhattan Transfer 152: Burglary, adultery, sneaking down fireescapes, cattreading along gutters. Judas it’s a great life.
1930		K. Brush Young Man of Manhattan 322: Judas! What wouldn’t I give —.
1931		G.S. Schuyler Black No More (1971) 113: Judas Priest! You got in on the ground floor, didn’t you?
1932		R. Fisher Conjure-Man Dies 294: ‘Judas H. Priest!’ said Perry Dart softly.
1934		R.E. Howard ‘Mountain Man’ in Action Stories Mar.–Apr. 🌐 Oh, Judas Iscariot, we’re blowed up now!
1938		W. Smitter F.O.B. Detroit 204: ‘Judast!’ said Russ.
1940		S. Sterling ‘Ten Carats of Lead’ in Black Mask Stories (2010) 234/1: Judas Priest! They marked you up, didn’t they?
1960		G.W. Target Teachers (1962) 66: And Judas Priest! what a bloody mess!
1974		V.E. Smith Jones Men 154: Judas Priest! What in hell’s going on around here?
1990		S. King Dark Half (tie-in edn) 159: Judas Priest! The Sheriff — Alan — said if you was to call, I should see you got through [...] Judas Priest! I’m a damn lunkhead!