«Gehenna», Jewish Encyclopedia. Sitat: «The place where children were sacrificed to the god Moloch was originally in the "valley of the son of Hinnom," to the south of Jerusalem (Josh. xv. 8, passim; II Kings xxiii. 10; Jer. ii. 23; vii. 31-32; xix. 6, 13-14). For this reason the valley was deemed to be accursed, and "Gehenna" therefore soon became a figurative equivalent for "hell."»
newadvent.org
«Hell», Catholic Encyclopedia. Sitat: «However, in the New Testament the term Gehenna is used more frequently in preference to hades, as a name for the place of punishment of the damned. ... held in abomination by the Jews, who, accordingly, used the name of this valley to designate the abode of the damned (Targ. Jon., Gen., iii, 24; Henoch, c. xxvi). And Christ adopted this usage of the term." Jewish Encyclopedia: Gehenna: Sin and Merit: "It is frequently said that certain sins will lead man into Gehenna. The name "Gehenna" itself is explained to mean that unchastity will lead to Gehenna (; 'Er. 19a); so also will adultery, idolatry, pride, mockery, hypocrisy, anger, etc. (Soṭah 4b, 41b; Ta'an. 5a; B. B. 10b, 78b; 'Ab. Zarah 18b; Ned. 22a).»
