The introductory statement (1:1-3) establishes Jeremiah as a historical person and his book as a theological document. See other commentaries for detailed descriptions of the historical, geographical, and cultural setting of the book.
The ministry of a true prophet in Israel was guided by the strong conviction that he was under constraint by a divine call to speak on behalf of Yahweh. The account of Jeremiah's call (vv. 4-19) is much like the call accounts of Moses (Ex 3:1-4:17), Isaiah (ch. 6), and Ezekiel (1:1-3:15). “Before I formed you” and “Before you were born” (v. 5) imply that Yahweh bestowed his grace upon Jeremiah from the time of the prophet's conception in his mother's womb. Yahweh's words, “I knew you,” etc. (v. 5), are covenantal terms. God has established a special covenantal relationship with his spokesman before his birth. Therefore, the one being called is under obligation to obey the one who calls (see Isa 49:1; Gal 1:15).
Vv. 6-7 demonstrate the theological principle that Yahweh's decision to call one to be his spokesperson is not guided by the human tradition that words of wisdom are with the experienced (see Mt 21:16; cf. Ps 8:2). Furthermore, he equips the one being called with the promise of his presence (v. 8), with his personal touch (v. 9), and by placing his words in one's mouth (15:16; Eze 3:2; cf. Dt 18:18). Jeremiah's task is to announce to the nations the promptness with which Yahweh is about to fulfill his threats and promises (vv. 10-16; see Clarke, 256). Contemporary political powers are the instruments of Yahweh's judgment against the wicked and the disobedient (vv. 13-16).
Yahweh expects faithfulness and courage from his spokesman—faithfulness in proclaiming judgment and courage to encounter opposition (vv. 17-19). “I am with you” (v. 19; also v. 8) is an assurance of protection and safety. God is determined “to defend and support” his prophet (Clarke, 257). Implied here is a call to abandon self-sufficiency and to trust in the presence and power of God (see Ex 3:12; Mt 28:20b).