"Why has the promise of a coming Messiah [not been fulfilled yet]? After all, since the time our ancestors died, everything has continued the same, even since the beginning of creation!"

The Lord is not slow about keeping His promise, like some people are, but is [simply] being patient with you, since He does not want anyone to be destroyed, but He wants everyone to repent [i.e., change their hearts and lives].

Since all these things are [certain] to be destroyed, what kind of persons should you be, [if not like those] living holy lives, and in a godly manner,

But, since God has promised it, we look forward to new heavens and a new earth, where righteousness will prevail.

Therefore, dearly loved ones, since you know about these things ahead of time, be on your guard so that you are not led astray by the error of lawless people, and [thus] fall from your own stability [i.e., your safe or secure position in Christ].