20 Things You Didn't Know About The Omen
7. Father Brennan's Biblical Quote Is, Unsurprisingly, Not In Scripture
Early in the film, a priest present at Damien's birth-by-jackal approaches Thorn to warn him. Father Brennan serves as an exposition dump/first victim in films like this, there to spout out some vaguely spooky-sounding Biblical passages before being dispatched early in the second act.
His character is the religious equivalent of the slasher movie's gas station harbinger who warns the teens of the danger. Similar Father Brennan roles appear in everything from End of Days, where Rod Steiger steals lines from The Usual Suspects, to The Sentinel, where John Carradine appears for 30 seconds to reveal the twist.
So you have to give to Seltzer; his novice knowledge of scripture freed him from the constraints of the Good Book. He just flat invented his own spooky sounding Bible stuff. We'll leave it here, for you to enjoy, but do so knowing it's not contended text that scholars have argued upon; it's just about of hooey.