The teaching of hell is under considerable attack. This isn't surprising - it's a fearful thing to contemplate.
However, one strand of attack says that the teaching of hell was unknown in the Old Testament, but was invented by Christ. Now in responding to objections it's important that we see what would follow if the objection happened to be true. Let's say for a moment that the teaching of hell was unknown in the Old Testament; let's say that Christ was the first to teach it. What follows from that? Does that mean then that hell doesn't exist? Would it not be reasonable to expect that Christ revealed certain things that no one else could have known?
Furthermore, in Romans chapter 1 Paul states that human beings know intuitively that there is judgment for their sins (Romans 1 v 32 - note that death here is not the death penalty because many of the sins listed didn't carry the death penalty, but it refers to being cut off from God). So this knowledge of judgment to come is one that God places on the hard-drive of every human. This is the reason we feel guilt - we have an in-built knowledge of our moral obligations and a sense of foreboding and dread, a recognition we deserve punishment, when we fail to fulfil those obligations.
So this would mean that Christ expanded upon and expounded upon the innate knowledge humanity already had. The Lord filled in the details.
But, is it true that the Old Testament didn't teach about hell? Well, no. Certainly it is not as detailed, but it is there nonetheless. I want to show you that it's in each of the major divisions of the Old Testament (Luke 24 v 44) - the Law, the Poetical books, and the Prophets.
The reason there is this notion that the Old Testament doesn't speak about hell is because the Hebrew word that is often translated "hell" (Sheol) is equivocal - that is, it doesn't mean the same thing all the time. The word basically referred to the location of people after death. Sometimes it referred to their bodies, and other times it referred to their souls. People have jumped on the references where the body may be in view and have proclaimed victory - "Sheol means grave!" But this is a childish attitude to take because although there are some passages that may demand nothing more than it being the grave there are other passages that demand the word meaning much more than just the grave. Note the following:
In Numbers 16 the rebellious sons of Korah were judged by the Lord and went alive into Sheol (translated "the pit" here). A fair reading of the passage will tell you they didn't go alive into the grave, nor would it make any sense to say that they went alive into physical death (meaning others would go dead into physical death!) - they departed into the unseen world to a place of judgment without passing through death.
In Deuteronomy 32 v 22 the Lord says, "For a fire is kindled in Mine anger, and shall burn unto the lowest hell." If someone were to say this is figurative language, my question would be "Figurative of what?" What sense would it make to use metaphoric language about burning to the lowest grave or the lowest death? The language shows that the Hebrews believed there was more to Sheol than the place where the body went.
Moving into the poetical section of the Bible we again see that people believed in the existence of an unseen world after death. Job speaks about the depths of hell (11 v 8) - what could that mean in purely materialistic thinking?
In chapter 26 he speaks about how the unseen is seen by God - "Hell is naked before Him, and destruction hath no covering." It's clear Job isn't thinking about earthly matters here, but things which we can't see.
In Psalm 9 v 17 David says the wicked shall be turned into hell. Are we to believe he is merely saying that they are going to die? Sure so are we all! He wasn't saying that the wicked die prematurely because that just isn't always true, and we find that what vexed another psalmist was that the wicked seemed to live long and prosper on the earth, but then he remembered their ultimate destination (Psalm 73 v 1-17).
Moving on to the prophetical section of the Old Testament, we find further confirmation of the reality of conscious punishment after death. In Isaiah 14 v 9-10 we find someone going to hell and the dead speaking to him! It is also important to see that he is not in the grave (v19, 20), so if Sheol is just the grave we have big problems because he's in Sheol but he's not! It is clear that his soul is in hell but his body is not afforded the honour of burial.
Other passages could be cited but I think enough has been said to show that Sheol does have as one of its meanings a place of misery where the soul of the unforgiven goes after death.
There are other factors to be considered. The prohibitions against the practice of necromancy (Deuteronomy 18 v 9-12) show us that there was an ingrained, deep-seated and wide-spread belief in the continued consciousness of the soul after death. God banned the practice in Israel, not because the dead didn't exist or weren't conscious, but because it is not our right to cross that line and seek communication with them. It is evident that it wasn't just the pagan nations but those in the nation of Israel believed in the survival of the soul after death, seen, for example, in the actions of Saul with the witch of Endor (1Samuel 28 v 7-20), and the words of David at the death of his infant son (2Samuel 12 v 23).
Finally, in Daniel 12 v 2 we see that there will be a resurrection of the saved and the lost. Body and soul will be reunited, and those who have not had their sins forgiven on earth will be subject to shame and everlasting contempt. Needless to say you can't feel shame if you don't exist, and there won't be everlasting contempt of people who don't exist.
The point then is that this teaching was not invented by Christ - it is a teaching that is as old as the Bible. The Son of God gave more details of it. The reason it's taught in the Bible is because it's true, and God doesn't desire you to go there. He tells us about it, not just so that we will be scared, but so that we will be saved. Although all of us deserve to be there none of us have to go there. Salvation is available because Christ suffered for our sins. All who drop their defense, plead guilty, and claim Him as Substitute will never perish. Those who don't receive the Saviour will forever perish.