Eternal - Vine's Expository Dictionary of New Testament Words
Eternal[ 1,,G165, aion ]
an age," is translated "eternal" in Ephesians 3:11, lit., "(purpose) of the ages" (marg.). See AGE.
[ 2,,G166, aionios ]
"describes duration, either undefined but not endless, as in Romans 16:25; 2 Timothy 1:9; Titus 1:2; or undefined because endless as in Romans 16:26, and the other sixty-six places in the NT.
"The predominant meaning of aionios, that in which it is used everywhere in the NT, save the places noted above, may be seen in 2 Corinthians 4:18, where it is set in contrast with proskairos, lit., 'for a season,' and in Philemon 1:15, where only in the NT it is used without a noun. Moreover it is used of persons and things which are in their nature endless, as, e.g., of God, Romans 16:26; of His power, 1 Timothy 6:16, and of His glory, 1 Peter 5:10; of the Holy Spirit, Hebrews 9:14; of the redemption effected by Christ, Hebrews 9:12, and of the consequent salvation of men, Hebrews 5:9, as well as of His future rule, 2 Peter 1:11, which is elsewhere declared to be without end, Luke 1:33; of the life received by those who believe in Christ, John 3:16, concerning whom He said, 'they shall never perish,' John 10:28, and of the resurrection body, 2 Corinthians 5:1, elsewhere said to be 'immortal,' 1 Corinthians 15:53, in which that life will be finally realized, Matthew 25:46; Titus 1:2.
"Aionios is also used of the sin that 'hath never forgiveness,' Mark 3:29, and of the judgment of God, from which there is no appeal, Hebrews 6:2, and of the fire, which is one of its instruments, Matthew 18:8; Matthew 25:41; Jude 1:7, and which is elsewhere said to be 'unquenchable,' Mark 9:43. "The use of aionios here shows that the punishment referred to in 2 Thessalonians 1:9, is not temporary, but final, and, accordingly, the phraseology shows that its purpose is not remedial but retributive." * [* From Notes on Thessalonians by Hogg and Vine, pp. 232,233.]
[ 3,,G126, aidios ]