A Word to the Remnant

In the final chapter, the prophet gives a word from the Lord to the faithful remnant, those who tremble at His Word. His intention is to give them hope and comfort during the judgment that is fall on the unfaithful hypocritical Jews who worshiped God in external appearance only, while their hearts were devoted to sin and abominations.
The principle here is that the true mark of salvation is perseverance by grace to the end (Matthew 10:22). Trials and troubles are designed of God to draw His people to seek Him and He fills their hearts with joy as the wait for Him and trust in His promises.