A People Return
While in exile, God delivers a pivotal message through His prophets Jeremiah and Ezekiel: the promise and hope of a new covenant. This new covenant will fulfill and surpass the old covenant. It will accomplish two main objectives - provide a radical change of heart from within, and vindicate God's Name among the nations. Every aspect of the new covenant will be fulfilled by God Himself: He'll create a united people, who will live under the reign of His Shepherd King, and who will enjoy the security and blessings of His Kingdom. The expectation is that when the promised Messiah arrives, He will initiate this new covenant.
As the Jewish people return from exile and begin the work of rebuilding Jerusalem and the Temple, it doesn't take long for them to fall back into old habits. Once again through prophets, God calls the people to a deeper faith, to see beyond their present experience to a greater glory yet to come. God remains faithful in bringing about what He has declared. This is how the New Testament begins as the Old Testament closes.