Green’s Dictionary of Slang

1. (US) a general intensifier, esp. with implications of assurance, arrogance.

1884		C.F. Lummis letter 15 Sept. in Byrkit Letters from the Southwest (1989) 4: A youthful looking Plug Ugly [...] emerged from the crowd with a ‘be-Jesus’ swagger.
1950		A.B. Guthrie Way West 256: She needs good men all right [...] but not just anybody. There’s too many by-jesus anybodies everywhere. [Ibid.] 257: ‘Whativer is wrong with the Irish?’ [...] ‘Niver a thing,’ Greenwood said back, ‘Niver a by-jesus thing.’.
1965		L. Haylen Big Red 53: Have a look at the sodden bejesused Paddy.
2020		T. Pluck ‘Hula Hula Boys’ in What Pluckery Is This? (28 Jan 2024) 🌐 [O]nce they were stoned to the bejeezus belt, she would reward them as she saw fit.

2. (Aus.) humble, self-effacing.

1989

B. Reed ‘Messman on C.E.’s Altar’ in Passing Strange (2015) 18: He hung around the Cahill Expressway [...] with a b’jesus mien, a mind-your-own-business.