Is hell eternal?

Yes (John 5:28-29; Matt. 25:46; Mark 9:43-48).  The Bible speaks of an eternal punishment…but also an eternal reward.  Let’s strive to remain faithful so God’s grace saves us from the former and brings us to the latter.

What’s the purpose of Judgment Day if we already know where we are going?

“Judgment” (krima) in the New Testament not only means “judgment” (cf. Rom. 2:3).  It also could refer to “the sentence of a judge.”  The same word is translated “condemn” in some verses (cf. Matt. 23:14).  Thus, one of the purposes of Judgment Day is to formally sentence or condemn the unsaved to an eternal hell.

Even though those who have already died and have spent Hades in either paradise or torment know their eternal fate already (Lk. 16:19ff) — as well as those still alive on Judgment Day who failed to rise to meet the Lord in the air (1 Thess. 4:13-18) — there’s still at least one more reason for a formal judgment to take place.  On Judgment Day God “will bring every deed into judgment, with every secret thing, whether good or evil” (Eccl. 12:14).  He “will render to each one according to his works” (Rom. 2:6).

Yet one’s works or deeds “follow them” after death (Rev. 14:13).  In other words, one’s influence for good or ill on others still exists after death, in some cases for quite a while.  On the day of judgment, the dead will find out just how “their deeds followed them,” what kind of influence they had on others after their death.  The saved will hear about the influence for good the memory of their lives and teaching had on others, while the unsaved will find out that they continued to be a stumbling block for others after death due to what they had said and done, and will have to give an account for it (Matt. 18:6-7).