"Shall not perish." What does the Lord mean by "shall not perish"?

How is the term used elsewhere in the New Testament?

Or those eighteen who died when the tower in Siloam fell on them—do you think they were more guilty than all the others living in Jerusalem? I tell you, no! But unless you repent, you too will all perish. (Luke 13:4,5—NIV)

Only one Greek word is used in the four Gospels for perish, and it often refers to physical death, as in the verse above. I would suggest John 3:16 means if we believe in Jesus Christ our body will be brought into a state of immortality by being raised from the dead.

We Christians have departed in our thinking from the good news the Lord Jesus came to bring. He came to us who are in bondage to the fear of physical death. He pointed out that if we will keep our faith steadfast in Him we can forget about dying. All that is meaningful to us in the way of living will be preserved forever.

Of course we will be separated from our physical body for a season. But life goes on as always. We keep on learning and growing in Christ. He declared us righteous when we received Him as our Savior. Now we shall be made perfect in Mount Zion, being prepared to return with Him and govern the nations of the earth.

The sons of God will be revealed along with the Lord Jesus. They will have the incomparable joy of lifting the curse from the earth and of serving as trees of life so the human beings on the earth can be changed from their flesh and blood animal existence into the liberty of the glory of children of God.

The sons of God will be alive as they never have been before. They will have access to the spirit realm, but they were created on the earth and the earth is their home.

Let us begin to think about living forever as people, not as disembodied spirits. Let us remember that all who leave relatives or properties or anything else for Jesus' sake will be given back with interest, in the present world, all they have forsaken. In the world to come they will have eternal life, that is, they will not just be alive on the earth but they will govern by the power of endless, incorruptible resurrection life.

The Lord Jesus came that we might have life, and not just life but an abundance of life, a crown of life. We are in the pursuit of such life, if we are a diligent disciple of the Lord.

If in this world we live according to our fleshly desires we shall reap corruption in the Day of Resurrection. If we choose instead to live in the discipline of the Holy Spirit we shall reap eternal life—not eternal existence in the spirit realm but real human life, although greatly expanded in quality and quantity, on a perfect earth.

Christian, set your heart on continuing to live forever. For if you live and believe in the Lord Jesus you never shall die! (from He Will Never Die)