Your last point is well taken and well said. However, your argument is against those who misapply the doctrine of predestination, which is both true and Biblical.
Consider Romans 8:28-30
And we know that God causes all things to work together for good to those who love God, to those who are called according to His purpose. For those whom He foreknew, He also predestined to become conformed to the image of His Son, so that He would be the firstborn among many brethren; and these whom He predestined, He also called; and these whom He called, He also justified; and these whom He justified, He also glorified.
Notice that Paul has focused his attention on a very particular group of people: those who love God. And just as you say, this would NOT include those who take a lax attitude toward righteousness and goodness, suggesting that it doesn't matter how much sin one commits. Such people prove themselves haters of God. Such people are not predestined to be conformed to the image of his son.
Notice also that Paul draws a straight, unbroken line from foreknowledge to glorification. If this weren't so controversial, it would be very encouraging. Predestination is not an indicator of salvation, as some have rightly pointed out. Rather, foreknowledge is the true beginning of salvation.
Paul's main point here is that God has set aside those whom he will conform to the image of his son, specifically the image Paul paints. Jesus is the model of our glorification. He was glorified after he was justified; He was justified after he was called; And he was called after he was previously "known" by the Father. The same is true of all those whom God will glorify. He justifies only those whom he "foreknew", meaning, he will glorify all those who walked with him in trust and obedience. The most salient question is this, "did God know you? Did Jesus know you?" Matthew 7:22-23