There are many passages of scripture that alludes to God’s vengeance upon the wicked. You see this in the fall of man (Genesis 3) and even the flood accounts (Genesis 6). You also see this later in Genesis 11 where God comes down and confuses the people’s language and dispersed them from there. There are examples of God’s righteous Judgment on those who are proud and haughty. There are instances where the Jews for a time had to face God’s judgment (you may read Isaiah and Jeremiah for their warnings).
I say this because when thinking about hell, it is always necessary to think of God’s righteous character and his nature and his relationship to evil and sin. So it is because God is holy and just and good and righteous (Void of anything evil) he must punish sin - Whether I have sinned or even the one in prison or even the guy who has only committed sin once or whether it is God’s people (The Jews) or the gentiles. You may read upon God’s impartiality in Romans 2:11.
The Scriptures say that there will be a day of reckoning, where all men are judged according to what they have done (Romans 2). The Day of Judgment is a day that is unknown to Man (1 Thessalonians 5 – which says that the day will come as a surprise).
Hell is place for those preserved for Judgment due to sin (I know when I was growing up I thought heaven was a place where God resides and hell was the place where Satan resides and I am in the middle of the two powers hoping to be found in heaven when I die. This is actually a false perception of Hell). One particular passage is found in Jude verses 4-7 where we see that it is preserved for not just for men and women who deny the master and Lord, Jesus Christ, but also it is preserved for the angels and demons that fell away as you may see this in Luke 10: 18 which is a verse taken from Isaiah 14:12. You may also read Matthew 25: 41-46. To scripture it is a place of torment as you can read from passages like Luke 16:22-25. The Scripture says that Hell is a place that is full of fire Jude 23 which also tells us that it is real and not just something that is experienced through the mind. So in other words not only as shown from Luke 16 that it is a place of torment (where none of our needs will be met) it is also a place of physical torment.
For those who turn from their sin and turn to Christ however will be saved. The reason is because Christ being God was able to live the righteous lifestyle that we could never do on our own due to (being in Adam and our own sins) and because He was also Man he was able to take the place of sinners (this allures back to the OT sacrifices where the Jews made sacrifices to pacify God’s anger against sins committed that year – Leviticus 16) and rising again three days later proving that God was pleased in His sacrifice. Therefore all who turn to Christ and trust in Him alone who took the wrath of God, may be imputed his righteousness and be saved. (John 3:16-17 – God sent his son so that whoever believes in Him will be saved, Romans 10:1-4 – Christ is the righteousness for those who trust in Him by faith alone, and Romans 5:12-21 – where Christ is said to be the new representative for those who have faith in Him).