Because the unbeliever dwells comfortably in the realm of darkness and (according to John 3:19-20) prefers that realm, shunning any light, and taking pleasure in the evil, their choices must be bound to the rules of that land.
There is no innate "freedom of choice" or even the ability to make a choice that was not completely consistent with the leadership of that realm of darkness. John 3 makes that very clear.
But, more to the point, the words of the Lord Jesus Christ, in John 6, state that acquiring light (life) is the direct intervention of the Father giving a person to Christ - that person in whom the Holy Spirit gives life. "Everyone who has
heard and learned from the Father, comes to Me." And in another place, "63
It is the Spirit who gives life; the flesh profits nothing; the words that I have spoken to you are spirit and are life." (Note the capital "Spirit" in comparison to "spirit.")
Therefore, the "natural" person, the one who prefers darkness, has no ability, desire and is even repulsed over any indication of the light is changed by the Holy Spirit's work.
Here is a very important point: The believer is a "New Creature." He will carry nothing of the old into eternity. The old will is not part of the new creature - not the body, not the mind, not the will, NOTHING. The old will dies with the mind and body. Teaching and preaching that attempt to present that the old will is some how changed are not correct in this thinking.
Therefore, believers war within themselves because the old will has no desire to be dominated into submission to the New Will. Believers mush "die daily."
2 Corinthians 5:
17 Therefore if anyone is in Christ, he is a new creature; the old things passed away; behold, new things have come. 18 Now all these things are from God, who reconciled us to Himself through Christ and gave us the ministry of reconciliation, 19 namely, that God was in Christ reconciling the world to Himself, not counting their trespasses against them, and He has committed to us the word of reconciliation.
The "new will" process is illustrated in Hebrews 8:10 and although this passage refers to Jeremiah's words, they also indicate the transformation of the unbeliever into the believer.
For this is the covenant that I will make with the house of Israel After those days, says the Lord: I will put My laws into their minds, And I will write them on their hearts. And I will be their God, And they shall be My people.
It remains then that the direct and purposed work of God brings to the heathen the new heart and new mind.
The old will remains bound to the realm of darkness, and is obliged to exert all manner of persuasion against the new will. One shackled to the old will (believer or unbeliever) will find no freedom of choice, no freedom of will, only bondage and death.
Jesus addresses the issue(s) of this thread in the following passage from John 8:
42 Jesus said to them, “If God were your Father, you would love Me, for I proceeded forth and have come from God, for I have not even come on My own initiative, but He sent Me. 43Why do you not understand what I am saying? It is because you cannot hear My word. 44 You are of your father the devil, and you want to do the desires of your father. He was a murderer from the beginning, and does not stand in the truth because there is no truth in him. Whenever he speaks a lie, he speaks from his own nature, for he is a liar and the father of lies. 45 But because I speak the truth, you do not believe Me. 46 Which one of you convicts Me of sin? If I speak truth, why do you not believe Me? 47He who is of God hears the words of God; for this reason you do not hear them, because you are not of God.”
The unbeliever has NO freedom of choice/will and NO ability to initiate change or reject the realm in which that person resides. For they are of that family.
Believers are the adopted, the heirs, the only who have true freedom of choice/will and the ability to choose the path of righteousness or unfruitful paths of unrighteousness.