so that in all things God may be glorified through Jesus Christ, to whom be the glory and the power forever and ever. Amen: This doxology (a short hymn of praise) has led some people to think that one original letter of Peter ended here and that another letter was later added to it. Doxologies in the New Testament do appear at the end of letters (Romans 16:25–27; Philippians 4:20; Hebrews 13:21; 2 Peter 3:18; Jude 1:24–25). Doxologies also appear at the end of major sections within letters (Romans 11:36; Galatians 1:5; Ephesians 3:21; 1 Timothy 1:17).
Since there is no textual evidence for two separate letters, it is better to understand this doxology as marking the end of a major section of the letter.