We were created with the free will, to either chose our predestination or reject it.
In the beginning of Genesis, you can read of the original design and how Adam and Eve, walked with God in the garden.
You have to also notice, God placed one choice, in the tree of knowledge of good and evil, that would end this relationship and end the predestination by free will.
Note: in relationship = one way out
The idea is saturated throughout the Bible if you look for it.
Deuteronomy 30:19 (King James Version) I call heaven and earth to record this day against you, that I have set before you life and death, blessing and cursing: therefore choose life, that both thou and thy seed may live:
There always seems to be two choices and God always tosses us the right one.
Note: out of relationship = one way in
Matthew 7:13-14 (King James Version)
13 Enter ye in at the strait gate: for wide is the gate, and broad is the way, that leadeth to destruction, and many there be which go in thereat:
14 Because strait is the gate, and narrow is the way, which leadeth unto life, and few there be that find it.
John 14:6-7 (King James Version)
6 Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.
7 If ye had known me, ye should have known my Father also: and from henceforth ye know him, and have seen him.
Even if someone totally grasps the reasoning back to God, it takes an act of free will to do so.
Matthew 22:14 (King James Version) For many are called, but few are chosen.
Even if you embrace what Jesus had to say, you still have a choice between embracing, His teachings as something good to live by or an actually relationship with Him.
John 1:12 (King James Version) But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name:
Last passage to meditate on...
Matthew 7:22-23 (King James Version)
22 Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works?
23 And then will I profess unto them, I never knew you: depart from me, ye that work iniquity.