And then shall they see the son of man coming in the clouds, with power and glory; and-then shall he send his angels, and shall gather his elect from the four winds, from the uttermost part of the earth, to the uttermost part of heaven Verily, I say unto you, that this generation shall not pass, till all these things be accomplished." This is decisive, and cannot be evaded.
2.

The Apostles and Primitive Christians believed that Jesus would come in that generation, as is evident from many passages of the New Testament.

Paul's Epistles to the Thessalonians prove this, and contain an argument to them, intended to allay their terrors, or their impatience.

John says in his first Epistle, chapter ii.

18, "Little children, it is the last hour; and as ye have heard that Antichrist should come, even now (or already) there are many Antichrists, whereby know that it is the last hour." Many passages of similar import might be brought forward.