The day of the Lord is the predominant theme of the Scriptures. Moreover, it is the event that ultimately unifies the Christian and Jewish Scriptures, for all hold to the ultimate divine end that God “has fixed a day on which he will judge the world in righteousness” (Acts 17:31). Furthermore, the day of the Lord is so dynamic and extraordinary that it creates a fundamental delineation of time: “this age” before the day and “the age to come” after the day (cf. Matt. 12:32; Eph. 1:21; Heb. 6:5). Human sin and depravity will progress until the end of this age when God judges humanity on the last day, rewarding the righteous with eternal life and punishing the wicked with eternal fire. Through the day of the Lord, God will initiate the age to come, which will go on in righteousness, peace, and joy for unending ages (i.e., “eternity”).  - John P. Harrigan, The Gospel of Christ Crucified, p.3