Jhn 3:15 that everyone who believes in him may not perish, but have life eternal. 16 For God so loved the world that he gave his only begotten Son, that everyone believing in him should not perish, but have everlasting life.
We know that Jesus and the saints rule the nations for a thousand years, but the ruling includes is condemnation and the execution of the second death penalty. The saints live forever, even though the matter is expressed differently: Luk 20:36 for they cannot even die anymore, because they are like angels, and are sons of God, being sons of the resurrection. – God and his Son live forever, but it is not always expressed using the word ‘aionios’.
Jhn 5:26 For just as the Father has life in himself, even so, he granted the Son to have life in himself. God is, however, eternal God as is said in Rom 16:26… according to the commandment of the everlasting God, made known for obedience of faith to all the nations.
1 Tim 6:16 who alone possesses immortality (ἀθανασία Athanasia) and dwells in unapproachable light, whom no man has seen or is able to see. To whom be honour and eternal might! Amen.
The saints are immortal, i.e. they live forever. They do not, however, live on earth, ruling with Christ forever. The eonian rulership, as well as the eonian judgment, will come to an end; 1 Cor 15:25 For he must reign until he has put all his enemies under his feet.
The “eonian” prize of the saints will end. Christ, saints and others who have received eternal life do not die and do not disappear because they have received life – ie immortality. The Millennial kingdom will end after the thousand years have passed. The kingdom of God itself remains forever.
In connection with immortality, I think we can talk about eternal life. However, one Bible scholar wants to keep the concepts clear; we can get immortality (immortality, ἀθανασία athanasia), but we are not promised ‘eternal life’. I think more important than the kind of conceptual hair-splitting, is to understand where in the Bible ‘perpetual’ does not mean endless, but God’s prescribed era (time period). In addition to immortality, the context may require the use of the word eternal, as Heb. 9:14 by how much more the blood of Christ, who through the eternal Spirit (aiōnios pneuma), offered himself without blemish to God, will purify your conscience from dead works for the serving of the living God