[Frumanchu]

Was Pharaoh and Egypt eternally doomed? Could he/it repent and be spared God's wrath?
Sure!
"At what instant I shall speak concerning a nation, and concerning a kingdom, to pluck up, and to pull down, and to destroy it; If that nation, against whom I have pronounced, turn from their evil, I will repent of the evil that I thought to do unto them."

You're arguing from a conditional statement. The second half of this verse is just as true under Reformed theology as it is under your theology.

[kidkosmic1]

"You're arguing from a conditional statement."

So what? What's your point?

It says, right there in Jeremiah 18, that God can say one thing (i.e. He WILL destroy a nation), but do another IF they repent!

"If that nation, against whom I have pronounced, turn from their evil, I will repent of the evil that I thought to do unto them."

How can God NOT DO WHAT HE PREVIOUSLY PRONOUNCED in Calvinistic theology?