According to scholar David Bentley Hart: “Much depends, naturally, on how content one is to see the Greek adjective αιωνιον, aionios, rendered simply and flatly as "eternal" or "everlasting."
Throughout the whole of ancient and late antique Greek literature, an "aeon" was most properly an "age," which is simply to say a "substantial period of time" or an "extended interval."
The Hebrew לְעֹולָ֥ם וָעֶֽד, which appears in verses such as Micah 4:5, was rendered in Greek LXX as εἰς τὸν αἰῶνα καὶ ἐπέκεινα, in Latin as in aeternum et ultra, and in English Bible translations usually as "for ever and ever".
[4] The formula has a prominent place in Christian liturgies of both the Latin Rite and the Byzantine Rite, in the Liturgy of the Hours and the Eucharist: Trinitarian doxologies ending with the formula conclude the Psalms (e.g., the Gloria Patri), many prayers spoken by the priest, and hymns such as Tantum Ergo by Thomas Aquinas or Veni Creator Spiritus.
Vernacular liturgical traditions often do not translate the Greek and Latin formula literally: English translations of Christian prayers issued in 1541 by King Henry VIII 1541 and appearing in the later Book of Common Prayer replace it with the phrase “world without end”; the German Lutheran tradition reads “von Ewigkeit zu Ewigkeit” (“from eternity to eternity”), which is probably based on Old Testament formulas such as Psalm 90:2, Jeremiah 25:5, and Nehemiah 9:5 (quoted in Hebrew, above).