ISB ~ 1 Corinthians 1 v8

the day of our Lord:Paul reminds readers of the Day of Judgment, when every thought, word, and deed will be weighed in the balance by Christ (Rom 2:5-10; 2 Cor 5:10; CCC 682).

• The “day of the Lord” is a recurrent expression in the OT. It is a day of fiery judgment when God takes vengeance on his enemies and vindicates the saints (Joel 2:30-32; Amos 5:18; Obad 15). Sometimes it refers to a day within history, as with the day of Jerusalem’s devastation in A.D. 70 (Zech 14:1-5; Mt 24); other times it refers to the last day of history, when Christ will come again in glory to judge the living and the dead (3:13; 5:5; Acts 10:42). Paul rewords the traditional formula (“day of the Lord”) to identify Christ with the divine Judge (“day of our Lord Jesus Christ”).