John 5
28 Marvel not at this: for the hour cometh, in which all that are in the tombs shall hear his voice, 29and shall come forth;
they that have done good, unto the resurrection of life;
and they that have done evil, unto the resurrection of judgment.
everyone (entombed) gets resurrected
There are those who are resurrected to life and this is eternal
“And this is the promise which he promised us, even the life eternal.” 1 Jo 2.25
(God’s Word is true, that which he promises is guaranteed to happen)
Then there are those who receive/undergo the resurrection of judgment
and are “cast into the eternal fire” Matt 18.8
and “suffering the punishment of eternal fire” Jude 7
Here’s Jude seven
Jude7
7Even as Sodom and Gomorrha, and the cities about them in like manner, giving themselves over to fornication, and going after strange flesh, are set forth for an example, suffering the vengeance of eternal fire.
This actually gives us a pretty good idea of what the bible means when it uses the word aiōnios for eternal. Are the fires of Sodom and Gomorrha burning today? No of coarse not.
Here’s what my commentary says.
41. Everlasting fire. Described elsewhere as “unquenchable fire” (see on ch. 3:12) and “hell fire” (see on ch. 5:22). All three refer to the fires of the last day that will devour the wicked and all their works (2 Peter 3:10–12; Rev. 20:10, 14, 15).
The word aiōnios, translated “everlasting,” or “eternal,” once, “for ever,” means literally, “lasting for an age,” in the sense of being continuous and not subject to capricious change. The ancient Greek papyri contain numerous examples of Roman emperors being described as aiōnios. The reference is to the continuous nature of their tenure—they held office for life. It is thus clear that the English words “everlasting” and “eternal” do not accurately reflect the meaning of aiōnios. Aiōnios, literally, “age lasting,” expresses permanence or perpetuity within limits; “everlasting” and “eternal” imply duration unlimited. The duration signified by aiōnios must, in each case, be determined by the nature of the person or thing it describes. In the case of Tiberius Caesar, for instance, aiōnios describes a period of 23 years, that is, the time from his ascent to the throne until his death.
In the NT aiōnios is used to describe both the fate of the wicked and the future state of the righteous. Following the principle stated above, that the durative quality of aiōnios is to be determined by the person or thing of which it is used, we find that the reward of the righteous is life to which there is no end; the reward of the wicked is death to which there is no end (John 3:16; Rom. 6:23; etc.). In John 3:16 “everlasting life” is contrasted with “perish.” In 2 Thess 1:9 the wicked are said to be “punished with everlasting destruction.” The expression does not signify a process that goes on forever, but an act whose results are permanent.
“Fire” is the means by which punishment for sin is inflicted (Matt. 18:8; 25:41). That “fire” is “everlasting,” aiōnios, does not signify that it is of endless duration. This is clear from Jude 7. Obviously the “eternal fire” that destroyed Sodom and Gomorrah burned for a time and then went out. Elsewhere, the Scriptures refer to the fires of the last day as “unquenchable” (Matt. 3:12), meaning that they will not be extinguished until they have burned up the last vestiges of sin and sinners (see on v. 12). For ‘olam, the OT equivalent of aiōnios, see on Ex. 21:6.