From this side of history, Jeremiah has great resolve. Yet the shifting political allegiances he interprets are not so different from our own uncertainties. Only in retrospect are Jeremiah's claims clear.
Back in the mid-1990s I wrote a book on sin. Each of us knows sin experientially, of course, but few of us know it comprehensively even in that way because we are parochial even in our sinning. So I had to study sin. For a couple of years I read about sin in the Bible. I read commentaries on the Bible, theological encyclopedia articles and books on virtue and vice.