That is why God has given us the promise of His kingdom but also threatened us with punishment. He would not have done that to people in the toils of necessity. He would not have laid down laws, he would not have given us exhortations if we had been prisoners of destiny.
We are free and the masters of our fate. Just because we can grow evil from lack of effort or virtuous striving, He uses the medicine of the fear of punishment to correct our course and the attraction of the hope of heaven to steer us towards wisdom.
Not only from this argument but from the way we normally behave, it is clear that our lives are not directed by fate.
For if fate were the cause of our actions rather than our free will, what justification have you for whipping the slave who is a thief? Why, if your wife has committed adultery, do you take her to court? When you do stupid things, why are you ashamed? Why are you intolerant of accusations and regard it as an insult if anyone calls you an adulterer or a fornicator or a drunkard or suchlike?
The myth of a compelling destiny is nonsense. Our lives are subject to no unavoidable fate. Everything, as I have argued, points to beauty of free will.