And that was the point I made in one of those posts, we have to beware of overlaying our 21st C thought over what was thought, said, and done in the mid 19th C. Most definitely, slavery is evil and that IS a settled issue. Today. But if by "settled" we mean 99% then, well that just wasn't the case in the early 1800's... it took the U.S.A. a couple hundred years to work through to what we see as settled thought today.
There is nothing "wrong" with fiery anti-slavery messages, as long as we remember in the 1800's there were 2 sides to the debate, neither of which had attained the 99% at that time.
So, focusing only on the evil southern preachers with their pro-slavery messages but ignoring the kind of fiery anti-slaver messages that on one hand built up the devout but on the other influenced men like John Brown, well, just seems to me to be not telling the complete 18th C story.
Meaning no disrespect to anyone here... the longer I study this stuff, the more convinced I am that it is some of the most complex history you could set yourselves to studying. It ain't easy, or clean, or obvious. (which is why it takes a home library of 67 gazzilion books
)