In our study, we look at the man that is known as the weeping prophet and the tears that he shed for his people. He spent almost fifty years begging the people of Judah to repent and turn to God but nobody did.
"The words of Jeremiah son of Hilkiah, one of the priests at Anathoth in the territory of Benjamin. The word of the Lord came to him in the thirteenth year of the reign of Josiah son of Amon king of Judah, and through the reign of Jehoiakim son of Josiah king of Judah, down to the fifth month of the eleventh year of Zedekiah son of Josiah king of Judah, when the people of Jerusalem went into exile." NIV translation
We are introduced to the prophet who was from Anathoth which was a city of refuge. If someone accidentally killed another man, then they could flee to the city for safety. God called him from this city to go to the people of Judah and call them to repentance in the face of coming judgement. We see here, a list of the rulers that came and went as Jeremiah faithfully proclaimed the word of God. As we see, they did not repent and so God brought judgement on the people and they were turned over to the enemy and taken into exile.
"The word of the Lord came to me, saying, 'Before I formed you in the womb I knew you, before you were born I set you apart; I appointed you as a prophet to the nations.'" NIV translation
We see here the fact that God had chosen him even before he was conceived to be a prophet with a purpose. Although you may not be called to be a "prophet to the nations", God knew you from before you were born and He also has work for you to do that He designed only for you (see Ephesians 2:10).
"'Ah, Sovereign Lord,' I said, 'I do not know how to speak; I am only a child.'" NIV translation
This is just like Moses (in Exodus 3) in that both of them felt inadequate to speak on behalf of God. In both cases, God used men not because of their ability to speak but because of their lack of ability on their own. God uses the humble people of this world to His glory.