How do we know that Jesus Christ preached to the spirits in prison?

1 Peter 3:19 indicates that Christ, in the Spirit, preached to the spirits in prison, referring specifically to those who disobeyed during the days of Noah. This moment emphasizes the nature of Christ's existence and activity prior to His incarnation; He was present, working through the Spirit in the lives of the prophets, including Noah. This serves as a profound reminder of the perseverance of God’s call to repentance, even extending to those who were ultimately unresponsive. Understanding this part of scripture also reminds believers that the gospel has continuously been proclaimed throughout history and that salvation is entirely dependent upon God’s sovereign grace.