We are created in such a way that as far as our inner being is concerned we cannot die. This is because we can believe in God and can also love God; so we can be joined to God by faith and love, and to be joined to God is to live forever.
Everyone who is born has this “inner being.” Our outer being is our inner being’s means of carrying out the intentions of its faith and love.
The inner being is what we call “the spirit,” and the outer being is what we call “the body.” The outer being, called the body, is adapted to functioning in an earthly world. It is cast off when we die. But the inner being, called the spirit, is adapted to functioning in a spiritual world. It does not die. If we have been a good person in this world, our inner being is then a good spirit and an angel; if we have been an evil person in this world, our inner being is then an evil spirit.
After the death of the body, our spirit has a human form that is visible in the spiritual world, just as it had a human form that was visible in this world. Our spirit enjoys the abilities to see, hear, speak, and have sensations, just as it did in this world, and is endowed with every faculty of thinking, willing, and doing, just as it was in this world. In a word, we are human beings in absolutely every respect, except that we are not clothed with the dense body we wore in this world. That we leave behind when we die, and we never put it back on.
This continuation of our life is what is meant by “the resurrection.” The reason people believe that they will not be resurrected until the Last Judgment, when the whole visible world is allegedly going to perish, is that they have not understood the Word. It is also because sense-oriented people locate life in the body and believe that unless their bodies are revived it will be all over for them.
Our life after death is the life of our love and our faith, so the kind of love and faith we have when we live in this world determines the kind of life that will be ours to eternity. It is a life of hell for people who have loved themselves and the world above all, but it is a life of heaven for people who have loved God above all and their neighbor as themselves. The latter are the ones who have faith; the former do not.
The life of heaven is what is called “eternal life.” The life of hell is what is called “spiritual death.”
The Word tells us that we live after death. It says, for example, that God is not the God of the dead but of the living (Matthew 22:32); that Lazarus was carried up into heaven after his death, but the rich man was cast down into hell (Luke 16:22, 23, and following); that Abraham, Isaac, and Jacob are in heaven (Matthew 8:11; 22:31, 32; Luke 20:37, 38); and that Jesus said to the thief, “Today you will be with me in paradise” (Luke 23:43).
from New Jerusalem, Sections 223-228