1580s, "damage to one's reputation," from French scandale, from Late Latin scandalum "cause for offense, stumbling block, temptation," from Greek skandalon "a stumbling block, offense; a trap or snare laid for an enemy."
The Greek noun in this form seems to be attested first in Septuagint (25 times) and the Greek New Testament (15 times) as "cause of moral stumblings," translating a Hebrew word meaning "a noose, a snare." The Biblical use is presumably figurative or metaphoric, and OED and others conclude that it is "certainly an old word meaning 'trap' " or a variant of one. Presumably, then, originally "trap with a springing device" (compare related skandalē "stick of a trap," the trigger which is pulled by the cord to spring it), if it is from PIE *skand- "to leap, climb" (see scan (v.), as is proposed in Watkins (Beekes is skeptical); also see slander (n.), which is another form of the same word.
The word is used in "Ancrene Riwle" (c. 1200), scandle, "discredit to religion resulting from bad behavior by a religious person," from Old French escandle, eschandle (12c.); Anglo-French scandle, and Latin scandalum. But the modern word likely is a new borrowing.
The meanings "malicious gossip" and "shameful condition, action, or event; that which causes scandal" are from 1590s; the sense of "person whose conduct is a disgrace" is by 1630s. Scandal sheet "sensational newspaper" is by 1884. Scandal-monger is from 1702.