Passage
And they shall fight against thee; but they shall not prevail against thee: for I am with thee, saith Jehovah, to deliver thee.
Jeremiah 1:19 (ASV)
Nearby Context
Jeremiah 1:17 Thou therefore gird up thy loins, and arise, and speak unto them all that I command thee: be not dismayed at them, lest I dismay thee before them.
Jeremiah 1:18 For, behold, I have made thee this day a fortified city, and an iron pillar, and brazen walls, against the whole land, against the kings of Judah, against the princes thereof, against the priests thereof, and against the people of the land.
Jeremiah 1:19 And they shall fight against thee; but they shall not prevail against thee: for I am with thee, saith Jehovah, to deliver thee.
Study Lenses
The verse centers on "shall", "fight", "against", "thee", and "prevail". It is saying that the verse draws attention to "shall" and "fight", so its meaning should be read from those terms before moving to application.
The prior verse says "For behold I have made thee this...", giving immediate footing for "shall" and "fight". In Jeremiah context, the local focus is covenant, worship, and faithfulness.
A plain takeaway is to answer the verse's own emphasis on "shall" and "fight" with trust shaped by these words, not by a vague optimism outside the passage.