Job asked that question thousands of years ago. "if a man dies, shall he live again?"
(Job 14:14). Where are the dead?
He received his answer directly from the Lord. “For I know that my Redeemer lives, and He shall stand at last on the earth; And after my skin is destroyed, this I know, that in my flesh I shall see God, Whom I shall see for myself, and my eyes shall behold, and not another. How my heart yearns within me!” (Job 19:25-27).
There are many philosophies about death. Some believe in annihilation (nothing beyond the grave), purgatory (season of suffering after death), reincarnation (returning to earth), universalism (everybody finally making it to heaven). Others believe in "soul sleep" (unconscious until the resurrection).
With so many philosophies abounding, it is imperative that we hear the Truth from the only One Who Knows. People's beliefs and philosophies will pass away, but His Words - encapsulated in the inspired Written Word - will remain forever. (Matt. 24:35).
Death in the Biblical sense is more than just the separation of body and soul & spirit. It is eternal separation from God Himself. Jesus said those who believe in Him would never die. “Most assuredly, I say to you, if anyone keeps My Word he shall never see death.” (John 8:51, John 11:26)).
For the Christian, “to die” means to “fall asleep” to this life and to awaken in the Presence of the Lord. "Because I live," He said, " you will live also.” (John 14:19). Jesus is not asleep in Eternity and neither will we be.
Jesus pointed out that the unsaved Rich Man did not sleep in the grave either. He opened his eyes in hell. Lazarus found himself in a Good Place. Both could think, speak, reason and feel. One was in torment, the other in paradise. (Luke 16)
He told the redeemed thief on the Cross. "Assuredly, I say to you, today you will be with Me in Paradise.” (Luke 23:43)
The apostle Paul knew this. “We are confident, yes, well pleased rather to be absent from the body and to be present with the Lord.” (2 Corinthians 5:80).
If he were going to "sleep" in the grave, wouldn’t it be better to live on earth as long as possible? “For I am hard-pressed between the two, having a desire to depart and be with Christ, which is far better...” (Philippians 1:23,24).
'The dead" are very much alive in the Presence of God. The disciples witnessed some of them talking with Jesus on the Mt. of Transfiguration. “I am the God of Abraham, the God of Isaac, and the God of Jacob. God is not the God of the dead, but of the living.” (Matthew 22:32).
What happens to Christians who die? Their bodies separate from their spirit-being. They go directly to be with the Lord and are destined to return with Him, at which time the resurrection of the body takes place. (1 Thess. 4, Jude v.4, 1 Cor. 15:51,52)).
The spirit-being of unbelievers go to the Place of the Departed (Hebrew "Sheol" / Greek "Hades") to await the Great Judgment Day. This is the "holding cell" of Hell (Greek "Gehenna") and a dreadful place. The first inhabitants of Gehenna will be the Antichrist and the False Prophet, followed by satan (Rev. 20:10). God made Gehenna for satanic forces. People choose to go there. (Matt. 25:41).
“And now, brothers and sisters, I want you to know what will happen to the Christians who have died so you will not be full of sorrow like people who have no hope. For since we believe that Jesus died and was raised to life again, we also believe that when Jesus comes, God will bring back with Jesus all the Christians who have died .. Then, together with them, we who are still alive and remain on the earth will be caught up in the clouds to meet the Lord in the air and remain with Him forever. So comfort and encourage each other with these words.”(1 Thessalonians 4:13-18 NLT)
“You will show me the path of life; In Your Presence is fullness of joy; at Your Right Hand are pleasure forevermore.” (Psalm 16:11)