Most orthodox theologians acknowledge that a sinner’s body is destroyed after he dies, but they assert that it is the “immortal soul” of a sinner that remains in torment forever. The concept of the “immortal soul” came mainly from Greek philosophy, and entered into Christian teaching mainly through two different pathways. The first way was from Jews who converted to Christianity. After Alexander the Great conquered Israel and Egypt in 332 BC, many of the Jews who lived there came to accept Greek beliefs as true, and when they converted to Christianity they brought those Greek beliefs (myths) with them. The second way the belief in the immortal soul entered Christianity was from the Greeks who converted to Christianity as the Christian Faith began to grow and spread.

It is widely believed that the “immortal soul” is a biblical concept, but it is never mentioned in the Bible. Much has been written showing the soul is not immortal, but it is too much information to expound in this commentary article. (See Graeser, Lynn, Schoenheit, Is There Death After Life, pp. 17-28; Edward Fudge, The Fire that Consumes, pp. 65-76; Leroy E. Froom, The Conditionalist Faith of Our Fathers, pp.529- 802; Anthony Buzzard, Our Fathers Who Aren’t in Heaven, pp. 208-225.)

-- Appendix 4 - Revised English Version

The soul can be destroyed

Instead, Jesus taught:

Do not fear those who kill the body but cannot kill the soul. Rather fear Him Who can destroy both soul and body in hell. -- Matthew 10:28 (ESV)

Ezekiel wrote:

The soul who sins shall die. -- Ezekiel 18:20 (ESV)

The author of Hebrews believed:

We are not of them who draw back unto perdition; but of them that believe to the saving of the soul. -- Hebrews 10:39 (KJV)

The spirit also dies

God is Spirit and God is immortal (Romans 1:22-23; 1 Timothy 1:17). Therefore, because we were made in the image of God, some believe that our spirits are immortal too.

However, there are no verse in the Bible that state that our spirits are immortal. Instead, Solomon wrote:

For what happens to the children of man and what happens to the beasts is the same; as one dies, so dies the other. They all have the same breath (spirit), and man has no advantage over the beasts, for all is vanity. All go to one place. All are from the dust, and to dust all return. Who knows whether the spirit of man goes upward and the spirit of the beast goes down into the earth? -- Ecclesiastes 3:19-21 (ESV)

Definition of death

Many scriptures show that when people die, they have no consciousness.

However, according to some "death" means "physically conscious but living without God". They base their reasoning on scriptures like:

And you were dead in the trespasses and sins in which you once walked, following the course of this world, following the prince of the power of the air, the spirit that is now at work in the sons of disobedience — among whom we all once lived in the passions of our flesh, carrying out the desires of the body and the mind, and were by nature children of wrath, like the rest of mankind. But God, being rich in mercy, because of the great love with which he loved us, even when we were dead in our trespasses, made us alive together with Christ. -- Ephesians 2:1-5 (ESV)

Obviously Paul was not writing his letter to a bunch of dead people and neither was he referring to physical death. In this context Paul used the word "dead" to highlight that trespasses and sin does not only partially hinder you, but it makes you "spiritually dead". In other words, a trespasser's spirit cannot respond just like a dead person cannot respond to anything.

We can tell that “death” does not mean “alive but separated from God,” is that the same Hebrew and Greek words that are used for the death of plants and animals are used for the death of humans. Dead plants and dead animals are not just “separated from God,” they are dead; totally dead. No part of them is alive anywhere once they die. Furthermore, there are no unique words for “dead” that apply only to humans but not to other things that die. The same words for “dead” that are used for humans are used for animals. But if humans “died” in a unique way that applied only to them—that is, if parts of them died, but some part of them lived on in the Lake of Fire even though the Bible said the person was “dead”—then there would have to be some unique vocabulary for humans that would describe their unique kind of “death.” If part of a human lived on when they were “dead,” but no part of a plant or animal lived on when they were “dead,” then we would expect that a special word for “death” would exist that described human death differently from animal death. But no such vocabulary word exists. The fact that the same vocabulary exists for the death of people and animals shows that the state of death is the same for all of them: “death” means “no life.” Ecclesiastes speaks of the death of humans and animals:

“For that which befalleth the sons of men befalleth beasts; even one thing befalleth them: as the one dieth, so dieth the other; yea, they have all one breath; so that a man hath no preeminence above a beast: for all is vanity. All go unto one place; all are of the dust, and all turn to dust again. -- Ecclesiastes 3:19-20 (KJV)

-- Appendix 4 - Revised English Bible

Critique

However, critiques raises the following arguments:

Lazarus

Critiques would argue that Luke 16 contradicts this view.

The word Hadēs occurs in the Greek New Testament ten different times (11 in the Byzantine text), and it always refers to the state of being dead or the state of non-existence except one time in Luke 16:23. In that passage, Jesus uses Hadēs in the same way that his Pharisee audience was using it—to refer to a place of the living dead. The Pharisees were one of the Jewish groups that took on the Greek belief that some of the humans who had died were alive in Hadēs, which explains why Jesus framed his parable of the rich man and Lazarus the way he did (Luke 16:23). When Jesus told that parable, he was not trying to debate with the Pharisees whether dead people were dead or alive, he was trying to make the point that they were being so hard-hearted that they would not believe the truth if someone came back from the dead and told it to them (Luke 16:31). -- Revised English Version Bible Commentary

"Lazarus" means "God is my helper". This name was appropriate to show how God helps the poor. If you start to read things from Jesus' parables which were not part of his intended message in the context of the parable, you will get to all sorts of weird conclusions.

Ghosts

Demons can and do impersonate the dead to further the Devil’s teaching that dead people are actually alive. Demons can affect the environment and cause noise or movement, cold or hot spots, or “hauntings,” and in basically that same way they can cause “ghosts” of different clarity to appear, including impersonations of dead people. Examples of this in the Bible include Job 4:15 and 1 Samuel 28:13-19 (what appeared to the medium at En-dor was not Samuel, but a demon. A medium cannot make a godly man come from the dead and speak to the living in disobedience to God. The demon is called “Samuel” because it impersonated him so well).

So many people have seen ghosts or apparitions that a 2009 Pew Research Center survey showed that 18% of U.S. Americans claim to have seen a ghost, and a 2013 Harris poll showed that 42% of U.S. Americans believe in ghosts, and in many countries of the world these figures would be much higher. Although some sightings are not legitimate, many are by people who are credible witnesses who had no reason or desire to see a ghost. Demons have an agenda to make people believe that death is not really death, so they appear to people as ghosts or apparitions, or they make things happen that cause people to believe dead people are alive. Seeing ghosts or experiencing paranormal spiritual occurrences is a major reason many people believe that humans live on in some form after they die.

-- The Dead are Dead - Spirit & Truth

Near-death experiences

Not one person in the Bible who was raised from the dead said anything about the afterlife. This includes people who had been dead for hours or days such as the Shunammite woman’s son (2 Kings 4:35), the man from Nain (Luke 7:15), the synagogue leader’s daughter (Mark 5:42), or Lazarus, who had been dead four days (John 11:39, 44). If they experienced anything good or bad after they died, it surely seems they would have talked about it. The fact that they did not talk about what they experienced, combined with the fact that no one asked them about it, is good biblical evidence that nothing happens in death — no thoughts or experiences — there is just the absence of life (Ecclesiastes 9:10).

-- The Dead are Dead - Spirit & Truth

Possible explanations for these are:

• Some might have make up stories based on the popular belief is about the afterlife, for various reasons like sensation, attention, publicity, to justify their beliefs, etc.
• Some might have been confused by demonic hallucinations.
• Some might have experienced a “dream-like” state, similar to the experience we sometimes have when we wake up unexpectedly from a deep sleep such that imagination and reality is temporarily blurred. These people might have actually recall images from their memories of their own culture, religion, books or movies they recently watched and confused with their recent experience.

Jesus ministered to "dead people"

Some believed that Jesus was active in hell, while being "dead" based on:

For Christ also suffered once for sins, the righteous for the unrighteous, that he might bring us to God, being put to death in the flesh but made alive in the spirit, in which he went and proclaimed to the spirits in prison, because they formerly did not obey, when God's patience waited in the days of Noah, while the ark was being prepared, in which a few, that is, eight persons, were brought safely through water. -- 1 Peter 3:18-20 (ESV)

Peter actually stated that Jesus did his proclamation after being resurrected. How, Jesus practically did it, is debatable is there were not much information recorded for us. This verse does not proof that Jesus or any other person was active while being dead.