The Scripture is very clear that the Life, that Christ brought to light in His resurrection, someday, will be for all mankind.
So then, as through one transgression
there resulted condemnation to all men,
even so through one act of righteousness
there resulted justification of life to all men.
-Romans 5:18- (NASB)
For even as, in Adam, all are dying, thus also,
in Christ, shall all be vivified.
Yet each in his own class:
the Firstfruit, Christ; thereupon those who are Christ's …
The comparison of Christ with Adam in these passages, excludes all human reasoning. Through Adam all the people (without any exception!) become sinners and mortals. Consequently, in exactly the same way, through one man, all the people will be vivified (=made alive beyond the reach of death) and justified. That is not an option, but a fact!
But what is the advantage of the believer? Does Scripture not say that only believers will be allotted life eonian?
For thus God loves the world, so that He gives His only-begotten Son, that everyone who is believing in Him should not be perishing, but may be having life eonian.
He who is fond of his soul is destroying it, and he who is hating his soul in this world, shall be guarding it for life eonian.
The point is that both texts, the one as well as the other, is true. One truth is that all people eventually will be raised to incorruption and glory. The other truth is that only those who believe will receive eonian life. This can only be understood if we understand what Scripture means by eonian life. By far, most people get these differences hopelessly mixed up. Yet the distinction is extremely simple. Incorruptible life means that life is not transitory and, therefore, permanent. Eonian life, however, means that life is connected with an eon. In reality, with the coming eon.
Verily, I am saying to you that there is no one who leaves house, or wife, or brothers, or parents, or children on account of the kingdom of God, who may not by all means be getting back manyfold in this era, and in the coming eon, life eonian.
The Scriptures, besides teaching about a "coming eon", also reveals "eons to come".
that, in the oncoming eons, He should be displaying the transcendent riches of His grace…
Christ will reign in those eons. In Scripture, they are called, "the eons of the eons" (usually translated "forever and ever"), because they will be transcendent, excellent eons. They will be surpassing eons, when compared, for instance, with "this present evil eon" (Galatians 1:4).
… The kingdom of this world became our Lord's and His Christ's,
and He shall be reigning for the eons of the eons…
The last, governmental act of Christ will be the dethroning of death. On that occasion, He will make alive (beyond the reach of death) the remainder of humanity who will still be dead ("in the second death"),.
For He must be reigning UNTIL He should be placing all His enemies under His feet. THE LAST ENEMY IS BEING ABOLISHED: DEATH. For He subjects all under His feet. (…) whenever all may be subjected to Him, then the Son Himself also shall be subjected to Him Who subjects all to Him, that God may be All in all.
In summary: only those who believe will receive the life of the oncoming eon(s). It are the glorious eons, when Christ will reign. When death, once for all time, as the last enemy will be abolished, the incorruptible, imperishable life will be enjoyed by all mankind. Then, no longer will it still be called life-eonian, for the simple reason that the eons then will be finished (will have consummated).
Translation: Peter Feddema