The resurrection of Jesus is central to the Gospel because it demonstrates that Christ conquered death (1 Cor 15.54-55). God became human in the Person of Christ, suffered death and was buried. But Jesus came through the other side of death, demonstrating that its power had been defeated: “The last enemy to be destroyed was death” (1 Cor 15.26). While ordinary humans might die and become extinct—Jesus, being God, was immortal and eternal. As such Jesus continued beyond the grave.
Jesus is called the firstfruits of the resurrection (1 Cor 15.20) because what is true of Jesus is also true for those who follow Him. Just as Jesus was raised to life, so too those who are saved will be raised to life and receive the gift of immortality which is bestowed by God:
For since death came through a man, the resurrection of the dead comes also through a man. For as in Adam all die, so in Christ all will be made alive. (1 Cor 15.21-22)
…this perishable body must put on imperishability, and this mortal body must put on immortality. (1 Corinthians 15.54)
There are a number of Old Testament texts which indicate that the dead do not continue to have conscious existence:
Humans’ fate is like that of the animals; the same fate awaits them all… All have the same breath; humans have no advantage over the animal… All go to the same place; all come from dust, and to dust all return. (Eccl 3.19-20)
When their breath departs, they return to the ground, and on that very day their thoughts come to nothing. (Psalm 146.4)
The dead know nothing. (Eccl 9.5)
They are now dead, they live no more; those departed spirits do not rise. You punished them and brought them to ruin; You wiped out all memory of them. (Is 26.14)
We are used to hearing the words “eternal life” and understanding them to mean “salvation—an eternity in heaven” and contrasting them with “damnation—an eternity in hell.” But eternal life in the Scriptures is contrasted with death, not an eternity of suffering. We almost need to use new words to translate these terms so that their original meaning is presented. I would suggest that we could substitute “immortality” for “eternal life” and “extinction” for “death.”
For example, we would then read:
“I tell you the truth, whoever hears My word and believes Him who sent Me has immortality and will not be condemned. He or she has crossed over from extinction to life.” (John 5.24-25)
The most famous of Bible texts is John 2.16:
For God so loved the world that He gave His only son so that whoever believes in Him would not be extinguished, but may have immortality
Romans 6.23 would read:
The wages of sin is extinction, but the gift of God is immortality.
1 John 5.11-12 would say:
God has given us immortality, and this life is in His Son. He who has the Son has life; but he who does not have the Son of God does not have life.
The result of this is that those who are not saved are not eternally tortured in hell, but are extinguished. This teaching is called conditional immortality—it means that only those who are saved receive immortality or eternal life, while the unsaved remain mortal and do not continue on eternally.
If it were true that even the unsaved will live forever, Jesus did not come to bring eternal life, since even those in hell will live eternally.