I think those are valid points Mickey. But I'm sure that we, or at least I am going to be accused of trolling and not sticking to the subject.
I don't think the original questions are valid because they take the word out of context. Jesus didn't teach in a legalistic, literalistic fashion. Indeed, Origen complained that non-Christians said that the Bible had to be understood literally, while other ancient Greek and Egyptian texts were to be understood allegorically. Here are some comments from the Catena Aurea.
Origen: The uninstructed refer the words to the destruction of Jerusalem, and suppose them to have been said of that generation which saw Christ’s death, that it should not pass away before the city should be destroyed. But I doubt that they would succeed in thus expounding every word from that, “one stone shall not be left upon another,” to that, “it is even at the door;” in some perhaps they would succeed, in others not altogether.
Chrys.: All these things therefore mean what was said of the end of Jerusalem, of the false prophets, and the false Christs, and all the rest which shall happen down to the time of Christ’s coming, That He said, “This generation,” He meant not of the men then living, but of the generation of the faithful; for so Scripture uses to speak of generations, not of time only, but of place, life, and conversation; as it is said, “This, is the generation of them that seek the Lord.” [
Ps 24:6]
Herein He teaches that Jerusalem shall perish, and the greater part of the Jews be destroyed, but that no trial shall overthrow the generation of the faithful.
Origen: Yet shall the generation of the Church survive the whole of this world, that it may inherit the world to come, yet it shall not pass away until all these things have come to pass. But when all these shall have been fulfilled, then not the earth only but the heavens also shall pass away; that is, not only the men whose life is earthly, and who are therefore called the earth, but also they whose conversation is in heaven, and who are therefore called the heaven; these “shall pass away” to things to come, that they may come to better things.
But the words spoken by the Saviour shall not pass away, because they effect and shall ever effect their purpose; but the perfect and they that admit no further improvement, passing through what they are, come to that which they are not; and this is that, “My words shall not pass away.” And perhaps the words of Moses and the Prophets have passed away, because all that they prophesied has831 been fulfilled; but the words of Christ are always complete, daily fulfilling and to be fulfilled in the saints. Or perhaps we ought not to say that the words of Moses and the Prophets are once for all fulfilled; seeing they also are the words of the Son of God, and are fulfilled continually.
Jerome: Or, by “generation” here He means the whole human race, and the Jews in particular. And He adds, “Heaven and earth shall pass away, but my words shall not pass away,” to confirm their faith in what has gone before; as though He had said, it is easier to destroy things solid and immovable, than that aught should fail of my words.
Hilary: For heaven and earth have in their constitution no necessity of existence, but Christ’s words derived from eternity have in them such virtue that they must needs abide.
Jerome: The heaven and the earth shall pass away by a change, not by annihilation; for how should the “sun be darkened, and the moon not give her light,” if earth and heaven in which these are should be no more?
Raban.: The heaven which shall pass away is not the starry [marg. note: sidereum] but the atmospheric [marg. note: aereum] heaven which of old was destroyed by the deluge.
Chrys.: He brings forward the elements of the earth to shew that the Church is of more value than either heaven or earth, and that He is Maker of all things. [marg. note:
2 Pet 3:5]