Your problem, along with others, is not understanding the essence of a JUST God, Predestination violates God as being a JUST God. The Predestination Paul was speaking about is the Predestination of ALL MANKIND via his shed blood, to life eternal, there is only ONE CATCH, everyone has free will, and thus they must except this free pardon.
If a Warden offered to pardon everyone on death row and five death row inmates refused that pardon, you couldn't then turn around and say the Warden forechoose who would be given life, and who would die, you would have to say that the Warden offered life to all, and 5 chose to die instead.
Thus the Predestination Paul was speaking about was the predestination that we would all need a Sacrificial Lamb, and God supplied that via foreknowledge.
I sometimes come across as being blunt with my defense of the scriptures, I hope you won't take it that way.
Your "via foreknowledge" left a question on my mind as to whether you understood what God saw by his foreknowledge. Psalms 53: 2-3, God looked down from heaven upon the children of men to see if there were any that did understand, that did seek God. Every one of them is gone back. They are altogether become filthy, there is none that doeth good, no, not one.
I believe that God would have still been a just God if he had let them all Go to hell, but by his mercy he choose to save some of them.
Although God did give mankind the freedom to choose how they wanted to live there lives here on earth, he did not give them the freedom to choose their eternal life, due to what he saw by his foreknowledge.
God purposes things, and all of his purposes prevail. God could have purposed to save all mankind, but he did not. I have a lot of question as to why God does and does not do certain things, but my thinking is on a much lower level than God's is.
I do not believe that God was surprised by all of mankind not seeking him, because scriptures tell us that God knows all things.