I have seen 2 Peter 2:6 used to support Annihilation, but in my personal devotions when I came to this passage, I paid close attention to it and read it in context. We say that Traditionalists fail by too often reading a text at face value without really digging in to see what the text is saying and I see that same problem here.
Below are the first 9 verses of II Peter 2.
1 But false prophets also arose among the people, just as there will be false teachers among you, who will secretly bring in destructive heresies, even denying the Master who bought them, bringing upon themselves swift destruction. 2 And many will follow their sensuality, and because of them the way of truth will be blasphemed. 3 And in their greed they will exploit you with false words. Their condemnation from long ago is not idle, and their destruction is not asleep. 4 For if God did not spare angels when they sinned, but cast them into hell and committed them to chains of gloomy darkness to be kept until the judgment; 5 if he did not spare the ancient world, but preserved Noah, a herald of righteousness, with seven others, when he brought a flood upon the world of the ungodly; 6 if by turning the cities of Sodom and Gomorrah to ashes he condemned them to extinction, making them an example of what is going to happen to the ungodly; 7 and if he rescued righteous Lot, greatly distressed by the sensual conduct of the wicked 8 (for as that righteous man lived among them day after day, he was tormenting his righteous soul over their lawless deeds that he saw and heard); 9 then the Lord knows how to rescue the godly from trials, and to keep the unrighteous under punishment until the day of judgment,
In verses 1-2 Peter says that false teachers are coming and they will convince many people to follow them and their sensuality.
Then in verse 3 is says that they will exploit you but, “their condemnation . . . is not idle” and “their destruction is not asleep.” I feel this is Peter assuring his readers that, “Don’t worry, they will get what is coming to them.” Then he backs up that assurance by giving three examples of when God sent temporal punishment to the wicked.
In verse 4 rebellious angels are sent into gloomy darkness and kept until judgement. This is definitely not talking about final judgment because he is keeping them UNTIL the judgement.
In verse 5 It talks about the flood.
In verse 6 it talks about the destruction of Sodom and Gomorrah. This is an example of what will happen to the wicked. When? To assume Peter is talking about final judgement here is a presumption.
Verses 7 and 8 talk about how God preserved Lot.
Then in verse 9 it wraps up by saying that “the Lord knows how to rescue the godly from trials, and to keep the unrighteous under punishment until the day of judgement.”
Verse 4 is clearly an example of God keeping the unrighteous until judgement. But verses 5 and 6 should also be about that. Especially since the emphasis is added about how God preserved Noah and his family and Lot. In order for this to be an assurance to Peter’s readers, he must be saying that the false teachers who will be persecuting the church is nothing new. It happened in Noah’s time and in Lot’s time and in each situation God preserved his people and brought the wicked under punishment UNTIL the day of judgement.
You could argue that not all wicked people suffer like Sodom and Gomorrah or are destroyed like in Noah’s flood. True, but they will all be “kept under punishment” until the day of judgement. Some do destroy themselves. We see sinners perishing unhappily due to a sinful lifestyles all the time. But the assurance here is that regardless of what is going on around us or how hopeless it might seem, the believers will be preserved, and the wicked will be kept under punishment until the day of judgement. For this reason, the destruction described in verses 5 and 6 are not something that happens after judgement and I don’t think we should take it as that. There are plenty of good passages that support Conditionalism. I don’t think this is one of them.