Can a wicked person kill a soul? If he can't explain how killing his soul can be a just punishment?
Does a person cease to have free will after 1000 years? If not, explain how God can know he will not mend his ways in the infinite future time that he would have had if his soul was not destroyed?
Most of 'Christendom' (so-called Christian but mostly in name only) teach an immortal or death-proof soul.
The Bible's soul is the person himself. After God breathed the 'breath of life' into life-less Adam then Adam came to life. All of Adam became a living soul according to Genesis 2:7
The Bible does Not teach that Adam ' had ' a soul, nor that Adam ' possessed ' a soul, but Adam was a soul.
At death mortal sinner Adam became a dead soul or person, a life-less soul or person - Genesis 3:19
According to Ezekiel 18:4,20 'the soul that sins dies ', so the teaching of a death-proof soul is false.
Death is what kills the soul or person. - Romans 6:23; Romans 6:7
Since we can't resurrect oneself or another we need someone who can resurrect us.
According to the Bible it is Jesus who can and will resurrect the sleeping dead.- Revelation 1:18
A person will always have free will, we are all free to act responsibly toward God.
This includes angels: Faithful angels have everlasting life, the un-faithful angels are destroyed.
By the end of the thousand years humanity on Earth will have reached human perfection (No leanings towards wrongdoing)
So, by that time those faithful will have proved themselves upright and faithful, so they won't revert back to wrongdoing.