This time, I will think about what can be said from the spirit living forever.

The spirit should not age. As the spirit ages, its function declines and the spirit approaches death. But a spirit cells break down little by little. A spirit may slow down aging. It has very little metabolism and does not change much. It only increases the lifespan. Aging does not stop and It will die someday. It is important to stop aging to live forever.

When cells no longer divide, metabolism decreases and organisms age. In order not to age, the cells must not stop dividing. The number of cell divisions is determined by the length of the genes, telomeres. To live forever ,by changing the gene, such limits will disappear.

It can't be done by humans. So it will be done in the heaven. The spirit must gets eternal life in heaven. While on the ground, the spirit will not live forever.

It's hard to live forever with an old body. Without rejuvenation, there is no joy of living. Since the human race does not have it, the spirit will not rejuvenate while it is on the earth.

The spirit goes to heaven. There, the spirit will rejuvenate with a full body plastic surgery. The spirit modifies the gene. The spirit then obtains an eternal body.

In heaven, loving spirits want to have a baby
The spirit is almost the same as the human body. The spirit can give birth to babies. If an infant is like an adult spirit, it does not grow at all. The baby does not take a special surgical operation as an adult spirit. Then the baby will become an adult in a short time like a person.

To live forever, a spirit must go to heaven and remodel the its body. It is scientifically impossible for a spirit that cannot go to heaven to live for hundreds of years.