After the Israelites rebelled against Moses and Aaron and refused to enter the land God had promised to give them, they were forced to wander in the wilderness for forty years (Numbers 14:33). Eventually, the Israelites did enter the Promised Land, but their lack of faith continued to be a problem and they never completely overcame the enemies that surrounded them. As a result, the territory the descendants of Jacob occupied was in the end reduced to primarily just the city of Jerusalem.
In order to ensure that his promise to bless Abraham was fulfilled, God stipulated that a remnant of the people would be secured regardless of what happened to everyone else. He stated, “And ye shall be left few in number, whereas ye were as the stars of heaven for multitude; because thou wouldest not obey the voice of the LORD thy God” (Deuteronomy 28:62). Prior to the exile of Judah, God reminded his people several times that he intended to preserve a remnant of the people of Judah and enable them to return to their land after their captivity was completed. In fact, almost every one of the prophets from Isaiah on mentioned the remnant of God’s people in their message.
Jeremiah talked about the remnant that would be saved in the context of Babylon’s destruction. He said, “Therefore thus saith the LORD of hosts, the God of Israel; Behold, I will punish the king of Babylon and his land, as I have punished the king of Assyria. And I will bring Israel again to his habitation, and he shall feed on Carmel and Bashan, and his soul shall be satisfied upon mount Ephraim and Gilead. In those days, and in that time, saith the LORD, the iniquity of Israel shall be sought for, and there shall be none; and the sins of Judah, and they shall not be found: for I will pardon them whom I reserve” (Jeremiah 50:18-20).
The release of the remnant from captivity was based on a special one-time act of God that enabled the people to be forgiven without any atonement sacrifice. The Hebrew word translated pardon in Jeremiah 50:20, calach indicated a divine restoration of an offender into favor (5545). The reason this was necessary was because God could not bless anyone that had not been forgiven of all his sins. In essence, everyone that returned to the Promised Land after they were released from captivity had their slates wiped clean. There was no record of them ever committing a sin. It was the same as if they had been born again.