Everlasting describes that which has neither beginning nor end (as of God Himself — Ps 90:2), or that which, having a beginning, will never end (as of the life given to the redeemed — John 3:16, or the punishment of the wicked — Matt 25:46). In covenant language, God calls His covenant "everlasting" (berit olam) — He will never revoke it. The Everlasting Father (Isa 9:6) is not merely ancient but timelessly existent. The tension in Scripture is sobering: everlasting life and everlasting punishment are described with the same Greek word (aiōnios), in the same verse. The quality of eternity is determined by one's relationship to the Son.
EVERLAST'ING, a. Lasting or enduring forever; eternal; existing or continuing without end; immortal. In theology, the everlasting God is he who always was, always is, and always will be. Everlasting life is that life which shall never end; the life of the redeemed in the eternal state. Everlasting punishment is the punishment of the wicked, continued without end. EVERLAST'ING, n. Eternity; eternal duration. Also, a plant remarkable for retaining its color when dried.
Universalism — the doctrine that all people will ultimately be saved — has crept into mainstream evangelicalism largely by redefining aiōnios ("everlasting/eternal") to mean an "age-limited" rather than unending quality. This is exegetically dishonest: the same word describes both God's eternal nature and the duration of punishment in Matt 25:46. If eternal punishment ends, so does eternal life. Modern Christianity also suffers from a low view of everlasting things generally — the temporal dominates, the eternal is vague. People plan their finances for 30 years and their eternity not at all.
• Psalm 90:2 — "Before the mountains were born or you brought forth the whole world, from everlasting to everlasting you are God."
• Isaiah 9:6 — "And he will be called Wonderful Counselor, Mighty God, Everlasting Father, Prince of Peace."
• John 3:16 — "For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal (aiōnion) life."
• Matthew 25:46 — "Then they will go away to eternal punishment, but the righteous to eternal life." (Same word — aiōnios — for both.)
• Romans 16:26 — "…the eternal God…made known to all nations for the obedience of faith."
H5769 — olam (עוֹלָם): forever, everlasting, the age; time extending beyond the horizon in either direction; used in "everlasting covenant," "everlasting hills," "from everlasting."
G166 — aiōnios (αἰώνιος): eternal, everlasting; belonging to the age(s); used for God's nature, believers' life, and the punishment of the wicked.
• "The everlasting covenant is not a promise that may expire — it is secured by the blood of the eternal Son, and its guarantor cannot die."
• "The most sobering verse in the Gospels may be Matthew 25:46: the same adjective, the same duration, for two destinies determined by one question — did you know the Son?"
• "To live with eternity in view is not to neglect the present — it is to finally understand what the present is for."