This passage warns us of 'scoffers' who will come "in the last days;" scoffers, and their message. And in giving this warning, 4 world scenarios, or states, are presented. One of these scenarios - that presented by the scoffers - is false. The other 3 scenarios are all true, but at different times. And the apostle Peter mentions these TRUE scenarios to refute the teachings of the scoffers.
First of all, let's take a look at the picture painted by these scoffers. Their words are like those found in verse 4: "Where is the promise of His coming? for since the fathers fell asleep, all things continue as they were from the beginning of creation." They reason that since so many centuries have gone by without Christ's return, that He's not coming back at all! And their statement that "all things continue as they were from the beginning of creation" implies that they do NOT believe that God intervenes in worldly affairs.
But the apostle Peter says that people who say such things willfully forget past events. They willfully forget: in other words, they IGNORE certain historical facts.
And this leads us to the first TRUE world scenario, which is described in verses 5 and 6 as "the world that THEN existed." This is the world that existed in the days of Adam and Eve, Cain and Abel, Methuselah and Enoch - the days before the great flood. THAT world, we're told in verse 6, "perished, being flooded with water." So you see, just by looking into the past we can see that the statement of these scoffers in incorrect - all things have NOT continued as they were from the beginning of creation.
The second TRUE world scenario is described in vv. 7-12. That is, "the heavens and the earth which now exist." This scenario also will not last forever, for we're told in v. 7, "the heavens and the earth which now exist are kept in store by the same word, reserved for fire until the day of judgment and perdition (or destruction) of ungodly men." Now the scoffers of verse 3 are said to have willfully forgotten certain things. But in verse 8, WE are told NOT to forget one very important thing, and that is "that with the Lord one day is as a thousand years, and a thousand years as one day." There are those who believe that certain features of our earth took thousands, even millions of years to form. But according to the Scriptures God did those things in a matter of days. He created the earth and all this is in it in 6 days. He formed mountains and great canyons during a great flood which lasted only one year. We can look at these events and see that indeed, with the Lord, "one day is as a thousand years." It's been nearly 2000 years since our Lord's first advent; but with the Lord, "a thousand years [is] as one day." And verse 9 tells us that the delay is not due to slackness on God's part, but because He is longsuffering - because He is patient. He's giving US more time, so that more can come to know Him.
This world scenario, however, will also come to an end. We're told in verse 10 that "the day of the Lord will come as a thief in the night, in which the heavens will pass away with a great noise, and the elements will melt with fervent heat." The world of Adam and Eve, Cain and Abel, was destroyed by a great flood. The world as we know it today will be destroyed by fire after the 2nd coming of Christ.
This leads us to the third and final world scenario. In verse 13 we read, "Nevertheless we, according to His promise, look for new heavens and a new earth in which righteousness dwells." Of THIS world, God says, "the new heavens and the new earth which I will make shall remain before Me."
God is NOT slack concerning His promise. Jesus IS coming back, and this THIRD world will last forever; a world in which there is no death, no sorrow, no crying, no pain. A world in which God will make all things new. And by simply trusting in Jesus we can be guaranteed a place in this new world.