In the Old Testament, under the Old Covenant, God still used men and women not yet in the Commonwealth of Israel, and showed grace to them.
In this verse, Jeremiah prophesies peace and safety to an Ethiopian eunuch.
This servant in the house of the king of Judah had rescued Jeremiah before:
7Now when Ebedmelech the Ethiopian, one of the eunuchs which was in the king's house, heard that they had put Jeremiah in the dungeon; the king then sitting in the gate of Benjamin; 8Ebedmelech went forth out of the king's house, and spake to the king, saying, 9My lord the king, these men have done evil in all that they have done to Jeremiah the prophet, whom they have cast into the dungeon; and he is like to die for hunger in the place where he is: for there is no more bread in the city. 10Then the king commanded Ebedmelech the Ethiopian, saying, Take from hence thirty men with thee, and take up Jeremiah the prophet out of the dungeon, before he die. 11So Ebedmelech took the men with him, and went into the house of the king under the treasury, and took thence old cast clouts and old rotten rags, and let them down by cords into the dungeon to Jeremiah. 12And Ebedmelech the Ethiopian said unto Jeremiah, Put now these old cast clouts and rotten rags under thine armholes under the cords. And Jeremiah did so. 13So they drew up Jeremiah with cords, and took him up out of the dungeon: and Jeremiah remained in the court of the prison. (Jeremiah 38: 7-13)
Let us consider the types and shadows of our Lord Jesus in this passage.
"Ebedmelech" means "servant of the king". Jesus is the King of Kings, yet He submitted to the will of His father and became a servant for us:
"Let this mind be in you, which was also in Christ Jesus: 6Who, being in the form of God, thought it not robbery to be equal with God: 7But made himself of no reputation, and took upon him the form of a servant, and was made in the likeness of men:8And being found in fashion as a man, he humbled himself, and became obedient unto death, even the death of the cross.9Wherefore God also hath highly exalted him, and given him a name which is above every name:" (Philippians 2: 5-9)
God did not send His Son to save us because we worth saving. He loved us while we were still sinners (Romans 5: 8).
Returning to the account in Jeremiah, why does God promise to rescue the Ethiopian?
"For I will surely deliver thee, and thou shalt not fall by the sword, but thy life shall be for a prey unto thee: because thou hast put thy trust in me, saith the LORD." (Jeremiah 39: 18)
It's all about believing in God.
Why does God save us today? Because of anything that we did? Not at all! Because we believe in Jesus!
"For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life." (John 3:16)
"For by grace are ye saved through faith; and that not of yourselves: it is the gift of God: 9Not of works, lest any man should boast." (Ephesians 2: 8-9)
Notice also that Jeremiah comforts the Ethiopian, that even though he is afraid, God will protect him.
Today, let us rest in the promises of our loving Father. He is for us because of Jesus, who died for us and as us. He is taken us from death to life through His Son Jesus, and all God asks us to do is believe on His Son.