Gehinnom

"We already find in Ezekiel a part of Sheol distinguished as deeper, called the "pit" or "the lowest parts of the earth", where the uncircumcised descend and those who have fallen by the sword, causing terror in the land of the living. In course of time this distinction came to be more definite: the upper part of Sheol, destined for the just, was called "Abraham's bosom", and the lower part became Gehenna, where sinners were tormented in flames."

"The valley is mentioned several times in the Old Testament, first in Joshua 15:8, where it is called "the valley of the son of Hinnom", which in Hebrew is gei ben Hinnom. We don't know who Hinnom was, but his son apparently owned the valley at one point. A later reference calls it instead Hinnom's own valley—that is, in gei-hinnom. Later, that term, gehinnom, came to be Gehenna. It is normally identified as the ravine southwest of Old Jerusalem."

"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"."