We live in the fulness of time. Hence, we understand that for God all things are present. We commune with Jesus, Abraham, Mary, and Francis all at one time. We understand that the sacrifice of Christ is present and fulfilled everytime we are in His presence. Eschatology, the study of the end time, is not a study of one event that is chronologically bound.
Eschatology is how things are fulfilled.
If Cosmogeny is truly the study of the sacred accounts of creation then Eschatology is how creation is to be fulfilled and how it is shown to have sacred meaning. Jesus sheds His blood once and for all on Calvary, at the holy table, and whenever His people worship. And I am certain that many people lived in a time before Christ, just as many lived afterwards. The imagery in the Epistle to the Hebrews tells of Christ our High Priest entering into the Holy of Holies in the heavenly temple, sitting down at the right hand of the Father, and making eternal mediation for us with His own Blood. Yes, of course, because they existed in the arrow of time the Sacrifice was not yet present upon the earth.