John Calvin Commentary Matthew 24:34

"Verily I say unto you, This generation shall not pass away, till all these things be accomplished." — Matthew 24:34 (ASV)

This generation shall not pass away. Though Christ employs a general expression, yet he does not extend the discourses to all the miseries that would come upon the Church, but merely informs them that before a single generation has been completed, they will learn by experience the truth of what he has said. For within fifty years the city was destroyed and the temple was razed, the whole country was reduced to a hideous desert, and the obstinacy of the world rose up against God. Furthermore, their rage was inflamed to exterminate the doctrine of salvation, false teachers arose to corrupt the pure gospel by their deceptions, religion suffered tremendous shocks, and the whole company of the godly was miserably distressed. Although the same evils were committed in uninterrupted succession for many ages later, yet what Christ said was true: that before the end of a single generation, believers would feel in reality, and by undeniable experience, the truth of his prediction; for the apostles endured the same things that we see today.¹⁵⁵

Yet it was not Christ's design to promise his followers that their calamities would end within a short time (for then he would have contradicted himself, having previously warned them that the end was not yet); but, to encourage them to persevere, he expressly foretold that these things related to their own age. Therefore, the meaning is: “This prophecy does not relate to evils that are distant, which posterity will see after the lapse of many centuries, but to those which are now hanging over you and ready to fall in one mass, so that there is no part of it which the present generation will not experience.” So then, while our Lord heaps upon a single generation every kind of calamity, he by no means exempts future ages from the same kind of sufferings, but only instructs the disciples to be prepared to endure them all with firmness.

¹⁵⁵ “Que nous voyons aujourdhui advenir aux fideles;” — “which we see in the present day happen to believers.”;” — “which we see in the present day happen to believers.”