King David spoke of a lifetime being 70 or 80 years. So when the parable of the Fig Tree says that once Israel begins to flourish again, the Return of Christ will happen within a generation, does he mean within 80 years?
King David in a time of almost continuous war spoke of the life-span being 70 or 80 years. However people lived shorter lives or much longer lives, both before and after David.
Public hygiene makes a huge difference. With improvements the chemical, pharmaceutical industries claim that today's longevity is due to their medicinal productions, while others have attributed it to better water quality, cleanliness and understanding of the natural laws of health.
What was the length of a generation in the time of Christ when he said 'that generation (of the fig tree revived) shall not pass away"?
The Esseans and their Egyptian-based brethren the Therapeutae (the Greek actually means worshippers of God) lived long. These two groups identified with believers of the pre-Christian and Nazarene period were known as physicians expert in healing (asiai) as were the Nazarenes. How long did they live? We have the witness of Hegesippus of the first and second century, recorded in Eusebius Ecc History book 3, ch 32. Symeon, son of Clopas, was a cousin of Jesus who around 100 CE was the successor of James, the superintendent (bishop) of the Temple.
2. Hegesippus, whose words we have already quoted in various places, is witness to this fact also. Speaking of certain heretics he adds that Symeon was accused by them at this time; and since it was clear that he was Christian, he was tortured in various ways for many days, and astonished even the judge himself and his attendants in the highest degree, and finally he suffered a death similar to that of our Lord.
3. Here's what Eusebius wrote:
"But there is nothing like hearing the historian himself, who writes as follows: Certain of these heretics brought accusation against Symeon, the son of Clopas, on the ground that he was a descendant of David and Christian; and thus he suffered martyrdom, at the age of one hundred and twenty years, while Trajan was emperor and Atticus governor...
6. "And after being tortured for many days he suffered, and all, including even the proconsul, marvelled that, at the age of one hundred and twenty years, he could endure so much. And orders were given that he should be crucified."
Atticus was Roman Legate from 99 to 102 CE.
7. When did the Fig Tree begin to flourish again?
Was it in 1967 when Jerusalem was liberated?
Was it in 1948 when the State of Israel was declared?
Was it in 1920 when world powers declared that a Mandate so that all Jews could reclaim the land that belonged to them and which they had continually claimed for nearly 2000 years of exile?