This sermon emphasizes that believers can fully trust and obey Scripture because it comes from the changeless God. Peter’s eyewitness testimony confirms that Scripture is definitely reliable, its divine origin shows that it is divinely inspired, and the presence of false teachers proves that it is desperately needed. The sermon’s central idea is: “Our changeless God has given us His timeless Word.” Therefore, believers should tell the story, trust the story, and test the stories they hear by remaining grounded in God’s Word.