Jeremiah 1:5

Jeremiah 1:4-5 (see also Psalm 139:16; Galatians 1:15)
Now the word of the LORD came to me saying, “Before I formed you in the womb I knew you, and before you were born I consecrated you; I have appointed you a prophet to the nations.”

John Calvin writes: “Similarly the Lord says in Jeremiah 1:5 that he knew Jeremiah before he was in his mother’s womb, though he calls him at last to become a prophet in God’s own good time.”  (John: Calvin, The Crossway Classic Commentaries, p.361, emphasis mine)

Calvin adds: “The Lord spoke in the first chapter of Jeremiah a little differently from Paul so far as the words go, but in the same sense: ‘Before I formed thee in the belly, I knew thee; I gave thee to be a prophet to the nations’ (I.5). For when he was not yet even begotten, God had sanctified Paul to the office of apostle, just as also Jeremiah to the office of prophet. But He is said to separate us from the womb because we are sent into the world for this purpose, that He may accomplish in us what He has decreed. The calling is delayed till its proper time, when God has adapted us for the task which He commands us to undertake. Paul’s words may therefore be resolved thus: ‘When it pleased God to reveal His Son by me, who called me as he had separated me.’ He wanted to show that this calling depended on the secret election of God, and that he was ordained as apostle, not because he had fitted himself for undertaking such an office by his own industry or because God had discerned that he was worthy of having it bestowed upon him, but because, before he was born, he had been set apart by the secret purpose of God.” (Calvin’s New Testament Commentaries: Galatians, Ephesians, Philippians and Colossians, p.20, emphasis mine)

Jeremiah was foreknown by God (v.4), had election in Abraham as a Jew, and was called as a prophet. This has no bearing on Calvinism unless the calling is irresistible. Like Moses, young Jeremiah was reluctant (v.6), both citing personal deficiencies. (Exodus 4:1, 10) God had to reassure both that He was with them. As for Moses, he was so resistant that the “anger of the LORD burned against Moses.”  (Exodus 4:14) The fact of the matter is that the calling to be a prophet can be resisted, just like with Balaam who sinned (Numbers 22:34), committed error (Jude 11) and was a false teacher. (Revelation 2:14) Obviously the calling is not irresistible, evident in the case of both Jonah, who certainly resisted, and also the apostle Paul himself, who had been kicking against the goading of the Lord. (Acts 26:14)

One member of The Society of Evangelical Arminians comments:The call of the prophet is not the call to salvation but to service. Paul uses the language of Jeremiah to describe his own call. John the Baptist is a bit different, but not as much as people often believe. He also is called as a prophet from the womb and is set apart as the preparer. While I believe all three of these men were saved in the common sense of the term, their call did not necessitate their salvation. God can even use unrighteous prophets for his purpose. (SEA, emphasis mine)

Psalm 139:16 similarly states: Your eyes have seen my unformed substance; and in Your book were all written the days that were ordained for me, when as yet there was not one of them.

The believer’s Judgment will be based upon whether we did what we were appointed to do. (1st Corinthians 3:10-15)