O LORD, I know that the way of man is not in himself; it is not in man that walketh to direct his steps. — Jeremiah 10:23
Did Jeremiah believe that man's destiny is predetermined, that freedom is a mental illusion, that we are built by DNA and the impinging vectors of our environment to be forced into a path that we must walk?
I think it is true that each of us has a destination, if not a destiny. I like the word "doom" as it is so often illustrated in The Lord of the Rings and The Silmarillion. There are obstacles we must encounter, quests we must follow, pressures we must endure as we are strengthened and empowered for the vast freedoms of eternity. We may attempt to reject our doom, but it is laid upon us; we will face it despite our choices. Yet we are meant to be free. Jesus said, "You shall know the truth, and the truth shall make you free." This implies that man, apart from the truth, is in bondage but also that liberty is attainable.
Though I am unable to offer comprehensive answer to the question of predestination, it is true that we are creatures of two realms. The material world does seem to function in a deterministic fashion at the macro level, and to the extent that we inhabit that world, we are subject to its laws. We are also, however, spirit — whatever that means — and subject to the laws of that realm. This is what Jesus was trying to explain to those with whom He contended in the 8th chapter of John. They claimed freedom based on their descent from Abraham. Jesus countered that it wasn't a matter of natural lineage but of their "obedience" to sin which made them slaves of sin. They were destined to obey sin because the will of man is enslaved.
The will seems to be an interface between the spirit and the body. Man is born with his will imprisoned by the life of the flesh. He may have a good, kind temperament. He may be the beneficiary of a positive environment and good parenting. Nevertheless, he is chained to the natural life and unable to make truly free choices. It is only when we learn who we are in and through the Logos that we can be free — as Jesus said, "If you continue in My Word, then are you My disciples."
As creatures of the material world, we find ourselves doing that which we would rather not do, and we fail to do what we would prefer to do. For I know that the law is spiritual; but I am carnal, sold under sin. For that which I do, I approve not. For what I would do, that do I not; but what I hate, that I do (Romans 7:14-15). There may be a fleshly adherence to the law but it does not bring righteousness. It can only assuage our guilt. The natural man can get along fine with religious observance until and unless he comes to the raw Reality as the children of Israel did at the foot of Sinai. Isaiah had a similar experience and a similar reaction: Woe is me! For I am undone, because I am a man of unclean lips, and I dwell in the midst of a people of unclean lips (Isaiah 6:5).
For many of us the inevitable response to a close encounter with the Spirit is a sense of fear and unworthiness. Our guilt and shame are magnified. Our failures loom large and seem to multiply until we feel there is no way possible to endure His presence. This is not a bad thing. It is the infinite holiness within us that was made in His image and likeness in harmonic vibration with the Infinite Holiness of the LORD of Hosts. Naturally, the natural man gets a little shaken by that experience. It is death to the natural when we live in the spirit. As noted above, Paul had this experience: O wretched man that I am! Who shall deliver me from the body of this death? ... So then, with the mind I myself serve the law of God, but with the flesh the law of sin. There is therefore now no condemnation for those who are in Christ Jesus, who walk not according to the flesh, but according to the Spirit. For the law of the Spirit of life in Christ Jesus has made me free from the law of sin and death (Romans 7:24-8:2).
When the Son has set us free, we are free indeed.