"Just as people are destined to die once, and after that to face judgment," (Heb 9:27)
Note that this verse says nothing about the nature of the punishment or the duration for those who are condemned. There are many verses like that. See also The Unforgivable Sin.
It’s easy to read eternal torment into those verses (if that's what you believe the Bible teaches).
“But what about the verses which say there will be eternal punishment for those who do not repent before judgment day?”
There are very few of those verses.
There are far more verses which say one or more of the following: God will be all in all, he will make all things new, Jesus died not only for our sins but for the sins of the whole world, he is the saviour of all people, sin and death will be destroyed, God’s mercies endure forever.
Since the majority of scripture should be used to interpret the minority, maybe it would be wise to take a closer look at the verses which mention eternal torment to see if they have been accurately translated. (And I would strongly recommend reading chapter 4 in The Inescapable of Love God by Thomas Talbott before doing so.)
Some verses can be translated in more than one way. When this is the case a translator will choose the translation which best fits with his or her theology. Now some believe that the verses which are used to support eternal torment could only have one meaning. They believe this because they have been using lexicons which do not give the full range of meanings of aiônios; and they have not bothered to take a careful look at how the the word was used in the writings of Jesus day. See Terms for Eternity: Aiônios and Aïdios in Classical and Christian Texts by Ramelli & Konstan (see also).
If we love truth more than our theology, we will carefully examine these things and adjust our theology accordingly.
The New Testaments Teaching on Punishment and Hell