So sin is a habit???? Our Lord Jesus saw the human condition differently:
Mat 7:11 If you then, who are evil, know how to give good gifts to your children, how much more will your Father who is in heaven give good things to those who ask him!
Joh 2:24 But Jesus on his part did not entrust himself to them, because he knew all people
We are not perfect, but neither are we without choices.
We have choices. We by nature choose to do evil things because it is in our hearts. That is why we are not perfect. And God commands perfection.
And how does the Calvinist suggest that that occurs? The Catholic accepts the Grace of God in order to come as close as he can, and accept God's Judgement as to who he did with the gifts of God ie the parable of the talents.
What does the Calvinist do and why should he do it?
You missed an "also" in my reply. But some sin can have a strong element of habit. Smoking is an obvious example. There is an old wise saying of some truth: 'that which you feed grows; that which you starve dies.'
We do have some degree of choice in what we feed and what we starve, with God's grace. Don't you agree?