The judgments of God are established in the law itself. In the law, there is no sin worthy of torture in a literal fire. The fire is the “fiery law” itself (Deut. 33:2). His Word is like a fire (Jer. 23:29), for its purpose is to cleanse, purify, and burn out the dross in order to bring forth a perfect, finished product. This is seen especially in the fact that the “flogging” that the second group of believers receive is spoken of in terms of “fire,” even though they are not burned in any literal sense. Luke 12:49 concludes that passage with Jesus’ statement:

49 I have come to cast fire upon the earth; and how I wish it were already kindled!

For full reading:

https://godskingdom.org/studies/books/the-restoration-of-all-things/chapter-2-universalism-vs-restorationism