Matt 24
35Heaven and earth will pass away, but My words will never pass away.
sounds very odd to say words are about to never pass away.
Heaven and earth symbolized old covenant Israel and the Mosaic Law. Please look at Isa 51:15-16 and Isaiah 65.
Isaiah 65:1-16 contrast two types of people. Unfaithful Israel as a nation and the remnant. The remnant were God's servants like the prophets and others who obeyed and followed God. In verse 17 it introduces the new heavens and earth. What does it say? The people are a joy and Jerusalem is a rejoicing. Not a physical creation. A people. The church. The same Jerusalem of Gal 4:26 and the one that was coming down out of heaven in 70 AD. That's why God says He will slay them (unbelieving Israel) and call His servants by another name. He was slaying the unbelieving Jews as Matt 22:7 and Luke 19:27 say and the kingdom age was beginning.
That's why the last verse of Isaiah, Isaiah 66:24 says, "
And they shall go forth and look
Upon the corpses of the men
Who have transgressed against Me.
For their worm does not die,
And their fire is not quenched.
They shall be an abhorrence to all flesh."
Those are the bodies of the 1 million unbelieving Jews who died in Jerusalem in 70 AD.
Matt 24:35 is a figure of speech contrasting the passing away of the old covenant law and the new covenant never passing away. If you don't understand the figures of speech then it is easy to make mistakes and make the heaven and earth literal. All languages have figures of speech and prophecy is filled with them. That is a big reason why many men do not understand eschatology.