Before God created man He knew man would fall. He created a plan in which fallen man could come back to Him in fellowship.
Man freely chose to disobey God, proof that man has free will to choose God's way or his own way.
Predestination is man being chosen for this plan to be redeemed and conformed in the image of Christ.
But only the man who chooses to believe and obey Christ is chosen for this plan.
The Calvinist believes that God chose him to be conformed in the image of Christ. That is correct in a way but incorrect in another.
We plainly see in the Garden that God gave Adam the choice to obey or disobey Him, a total free will to choose.
Where Calvin went wrong is when he failed to see that God gave man this free will from the very beginning.
It was because of free will given to man, and man falling by His own choice, full well knowing the consequences, that man placed himself in separation from God.
In love an mercy by God, He gave us His Son, the Second Adam, to undo the wrong man had chosen, and give us an opportunity to come back into fellowship with Him through the Cross.
As in the very beginning with man, we have a choice to accept the gift of His Son, or reject it.