An atheist was attacking Jesus because He hasn’t returned in 2000 years (2 Peter 3:3-4).
A believer wrote: “Don’t you know that a thousand years to us is only a day to God? It’s only been 2 days!”
An unbeliever responded: “Jesus quite clearly said he would be back in his disciples lifetimes . He wasn’t . They are long gone .”
Jesus says “Assuredly, I say to you, this generation will by no means pass away till all these things take place” (Matthew 24:34; Mark 13:30; Luke 21:32).
The followers of Jesus asked 3 questions in these passages.
1) When will these things be?
2) And what sign will there be when these things are about to take place?
3) And what will be the sign of Your coming, and of the end of the age?
Jesus answered them.
As Jesus did not reveal to them the exact times that these things would take place, He was speaking to more than one generation. He knew the second coming would be in the future after Jerusalem was conquered by the Romans and liberated by the nation of Israel (Luke 21:24). Therefore it had to be two generations that He was speaking to. The two generations are the generation that would see the destruction of Jerusalem and the Temple, and the generation that would see His second coming.
In addition to that, John the disciple was transported through time and space to see the future revelation of Christ at His 2nd coming. He wrote it all down in the book of Revelation. So what Jesus has said is completely true, that generation did not pass away until a member of that generation witnessed the fulfillment of all His words.
Jesus is awesome. His wisdom confounds the “wise” people on the Earth. “For it is written: ‘I will destroy the wisdom of the wise, And bring to nothing the understanding of the prudent’” (1 Corinthians 1:19).