How do we know the day of the Lord is true?

The certainty of the day of the Lord is rooted in the consistent teaching of Scripture, which repeatedly emphasizes the reality of Christ's return and the resultant judgment. In 2 Peter 3:10, it is stated unequivocally that the day of the Lord will come as a thief in the night, signifying that the advent of Christ is assured despite scoffers who doubt. Additionally, Jesus Himself spoke on the matter, urging His followers to be prepared for His unexpected return, providing a cogent warning that underscores the significance of this future event. Historical Reformed theology also affirms these truths, advocating the importance of living in light of Christ's imminent return.