Mark 13:30 , “...generation will not pass away until all these things take place.”
Clearly all those then alive have died and yet these things he referred to have not all happened. Certainly the apostle Paul was expecting Jesus return within his lifetime. Many of Jesus parables gave that unmistakable interpretation. My Bible notes say that the word for “generation” can also be translated as “race”. In this context it is true; Israel still exists. But the common understanding of the word was “generation”. Indeed God wants us to live in the ever present expectation of His return because otherwise we will fall into all sorts of terrible practices. But you see how the common understanding can in the fullness of time be seen to have a different interpretation.