"Regarding
the false prophets in Jeremiah's day: did
they know that they were false prophets?
Or did they actually,
somehow, think that the LORD said those
things to them?
Were they only deceiving
others, or were they also being deceived?"
In regard to all false prophets and not just in
Jeremiah's day, I don't think the false prophets
knew they were false prophets. However, it
was a lying spirit that was sent to the false
prophets. So I think that both the false
prophets were deceived by the lying spirit and
the people they spoke to were also deceived by
the lying spirit.
If you read 1 Kings 22:19-23 &
1 Chronicles 18:18-22, the Lord asks for a
volunteer to be a lying spirit in the mouth of
the prophets.