I imagine a person can justify axe murdering by isolating certain verses at the expense of other verses that condemn murder. But that would not be reading the Bible in harmony. Romans 8:28-30 is not an exhaustive truth claim that ALL who are predestined will be glorified in the end. The passage makes no such claim. In fact, I highlighted the word “might” in the passage you quoted to me to show you that such a thing is not a 100% proof claim that those who are predestined will always be glorified.
Friend, I believe that it is! And to our encouragement! The golden chain of redemption tells us that the redemptive work of the triune God began in eternity past and is worked out in time unto eternity future.
Notice how Paul begins Romans 8:
There is therefore now no condemnation for those who are in Christ Jesus. For the law of the Spirit of life has set you free in Christ Jesus from the law of sin and death. - Rom. 8:1 (ESV)
We are freed from the bondage of sin and the penalty of death through Jesus Christ. Paul goes on to exclaim:
And we know that for those who love God all things work together for good, for those who are called according to his purpose. - Rom. 8:28 (ESV)
We have peace and security that everything that the Lord works in our life is for our good, even the sufferings (Rom. 8:18). Then Paul demonstrates the certainty of our salvation in the next two verses:
For those whom he foreknew he also predestined to be conformed to the image of his Son, in order that he might be the firstborn among many brothers. And those whom he predestined he also called, and those whom he called he also justified, and those whom he justified he also glorified. Rom. 8:29-30 (ESV)
What God determined in eternity past (foreknowing, predestining), he accomplishes in time (calling, justification) unto eternity future (glorification). The golden chain cannot be broken, meaning that each action applies to the elect all the way though. "Foreknew", "predestined", "called", "justified", and "glorified" each apply to the "those" at the beginning of Romans 8:29. Breaking the chain creates serious theological problems such as some who are justified not being glorified.
In addition: You have to take into account Matthew 13:41-42.
In this passage it says that the Son of Man (JESUS) will send forth His angels and they will gather out of HIS KINGDOM all things that offend (i.e. the word “offend” here is in reference to those who “offend” or make children to sin as mentioned by Jesus elsewhere) and those who work iniquity or lawlessness (sin) and they will be cast into the furnace of fire (i.e. the Lake of Fire).
In other words, a believer can be in the Kingdom and even be saved at one point in time, but they can later be cast out of Christ's kingdom on account of their justifying sin or a belief that makes room for a person to justify sin on some level. How scary that day of judgment will be for those who did not heed the words of Christ. For Acts of the Apostles 3:23 says that if any soul who does not hear that prophet (i.e. Jesus), they shall be destroyed. This even includes me, as well. For I am not above God's Word anymore than you are.
I believe that Matthew 13:36-43 is foretelling the day of judgment.
The field is the world, and the good seed is the sons of the kingdom. The weeds are the sons of the evil one, and the enemy who sowed them is the devil. The harvest is the end of the age, and the reapers are angels. - Matt. 13:38-39 (ESV)
The passage you quoted does not imply that "sons of the kingdom" (true believers) can "later be cast out of Christ's kingdom". It is speaking of the "sons of the evil one" (unbelievers) who are judged unworthy of the kingdom and cast into hell.
