So why then do most Christians, Jews and Muslims believe in hell? Why do most Christians believe in eternal damnation?
Jews executed Christ.
Muslims do not belive in the bible they believe in the Koran
Because the "main religions"of today or "Christendom" are based on the foundations of one church, back in the times of Rome. That church was originally started as an opposition to the the Christians that actually followed christ back then. (it is in their own encyclopedia on the foundations of the church itself) These Chrisitans were Burnt as Torches in those days. Then the Apostacy set in.
2 Thes: 2:3-5
Let no one seduce YOU in any manner, because it will not come unless the apostasy comes first and the man of lawlessness gets revealed, the son of destruction. He is set in opposition and lifts himself up over everyone who is called god or an object of reverence, so that he sits down in the temple of The God, publicly showing himself to be a god. Do YOU not remember that, while I was yet with YOU, I used to tell YOU these things?
So the beliefs of one chirch melded into another and false doctrines and Pagan beliefs (hellfire, eternal judgement in hellfire, purgatory, Trinity) all set in, yet none of these are actually supported in the bible.
It is all a total load of BUNKUM.