The word translated as visitation
means literally overseeing,
as in the day of overseeing (= inspection). Some questions arise.
Whose inspection is meant here? That is, who is the inspector? The phrase day/time of visitation
appears elsewhere in Scripture (Isaiah 10:3; Jeremiah 6:15; Jeremiah 10:15) to describe God as the inspector. That would distinctly be the sense in this passage too.
When is this day of visitation/inspection
? Jesus used the identical expression in Luke 19:44 to describe a day in the past, his own coming in his earthly ministry. Peter’s focus, however, clearly lies in the future. The term could refer to Christ’s return on the Last Day to judge the living and the dead, in which case the picture is that on the Last Day the Gentiles will glorify God on account of the good deeds they witnessed in those whom they had maligned and sidelined in this life (potentially centuries ago). The reference could also be to the day of the given Gentile’s death when he must appear before God the Judge. A third option is also possible: the Lord is free and able to visit/inspect (see Genesis 11:5; Genesis 18:21; Exodus 2:25) in the course of the years of New Testament history and through events he causes prompt Gentiles to acknowledge that the saints they marginalized were a blessing after all. There is really no need to choose between these three as all are in fact days of visitation.
12 Keep your conduct among the Gentiles honorable, so that when they speak against you as evildoers, they may see your good deeds and glorify God on the day of visitation.