Matthew 16:27 Jesus Christ has been given the authority to judge all the earth. Although His judgment is already working in our lives, there is a future, final judgment when Christ returns (25:31-46) and every one's life is reviewed and evaluated. This will not be confined to unbelievers; Christians too will face a judgment. Their eternal destiny is secure, but Jesus will look at how they handled gifts, opportunities, and responsibilities in order to determine their heavenly rewards. At the time of judgment, God will deliver the righteous and condemn the wicked. We should not judge others salvation; that is God's work.
Matthew 17:1 The Transfiguration was a vision, a brief glimpse of the true glory of the King. This was a special revelation of Jesus' divinity to three of the disciples, and it was God's divine affirmation of everything Jesus had done and was about to do.
Matthew 17:3-5 Moses and Elijah were two of the greatest prophets in the Old Testament. Moses represents the law, or the old covenant. He wrote the Pentateuch, and he predicted the coming of a great prophet (Deut. 18:15-19). Elijah represents the prophets who foretold the coming of the Messiah (Malachi 4:5, 6). Moses' and Elijah's presence with Jesus confirmed Jesus' messianic mission - to fulfill God's law and the words of God's prophets. Just as God's voice in the cloud over Mount Sinai gave authority to His law, God's voice at the Transfiguration gave authority to Jesus' words.
Matthew 17:5 Jesus is more than just a great leader, a good example, a good influence, or a great prophet. He is the Son of God. When you understand this profound truth, the only adequate response is worship. When you have a correct understanding of Christ, you will obey Him.