"God is no slouch when it comes to making and keeping a promise" (2 Peter 3:9, perryphrased version). Interview a few people on the street and you will discover that many do not believe in the return of Christ. They somehow feel that this particular promise has been swept under the rug or dropped into the useless drawer in the kitchen of life.
In other words...though God has kept all other promises, He won't keep this one. Peter found the same attitude when he interviewed people in his day. "Scoffers will come...saying, 'Where is the promise of His coming?'" (2 Peter 3:3-4)
Peter answered the scoffers by repeating the phrase, "by the word of God" (vs. 5, 7). The same "word of God" that made earth suddenly appear in the cosmos will cause Jesus and a billion angels to pop through the clouds above us in an instant.
Scoff away! Join the ranks of Noah's critics who said it wouldn't rain. It rained anyway. Grab a picket sign that reads, "Return of Christ" with a ghostbuster zero over it. Scoff till your heart's content. He will come anyway.
If your plane was delayed, would you take a nap on the runway? Not likely. There's a difference between "delayed" and "not coming." Jesus has not canceled His appointment, nor is He late. He will return right on time. But the Father keeps delaying because He wants to save one more soul.
Peter explained why the scoffers arrived at such a conclusion: "...this they willfully forget" (v. 5). Willfully forgetting is not like forgetting your car keys. It is a purposeful amnesia that implies motive. It's the "I forgot" that parole officers often hear from parolees who don't check in.
Do you think the parole officer buys that line? Neither does God.