While on earth Jesus did not know the day. But he obviously knew the day would happen. What we need to look at is if that day was something Jesus thought was about to happen or something that was thousands of years away.
Matthew 24:34
New American Standard Bible
34 Truly I say to you, this generation will not pass away until all these things take place.
Earlier in that chapter we read of these things like ā not one of these temple stones will be left ā and the temple was destroyed around 70ad.
He tells them if they are on their rooftops flee. That the abomination of desolation will come there .
Matthew 16:27-28
New American Standard Bible
27 For the Son of Man is going to come in the glory of His Father with His angels, and will then repay every person according to his deeds. 28 āTruly I say to you, there are some of those who are standing here who will not taste death until they see the Son of Man coming in His kingdom.
Here it says some wonāt even taste death at the coming of the kingdom.
This statement was also made.
Matthew 24:14
New American Standard Bible
14 This gospel of the kingdom shall be preached in the whole world as a testimony to all the nations, and then the end will come.
Jesus tells them to share the gospel with the whole world.
The whole world would first hear the message.
Matthew 28:18-20
New American Standard Bible
18 And Jesus came up and spoke to them, saying, āAll authority in heaven and on earth has been given to Me. 19 Go, therefore, and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit, 20 teaching them to follow all that I commanded you; and behold, I am with you always, to the end of the age.ā
Again Jesus tells them they will share it even the remotest places.
Acts 1:6-8
New American Standard Bible
6 So, when they had come together, they began asking Him, saying, āLord, is it at this time that You are restoring the kingdom to Israel?ā 7 But He said to them, āIt is not for you to know periods of time or appointed times which the Father has set by His own authority; 8 but you will receive power when the Holy Spirit has come upon you; and you shall be My witnesses both in Jerusalem and in all Judea, and Samaria, and as far as the remotest part of the earth.ā
They would go to Jerusalem, Samaria and the ends of the world. This is just speech for Jew, Samaritans ( half Jewish half gentile ) and ends of the world is just gentiles.
Then in acts 2,8 and 10 we see them going before the Jews, Samaritans and Gentiles.
But also what does Paul say?
Colossians 1:23
New American Standard Bible
23 if indeed you continue in the faith firmly established and steadfast, and not shifting from the hope of the gospel that you have heard, which was proclaimed in all creation under heaven, and of which I, Paul, was made a minister.
( heard under all of creation )
Romans 1:8
New American Standard Bible
8 First, I thank my God through Jesus Christ for you all, because your faith is being proclaimed throughout the world.
( throughout the whole world )
1 Thessalonians 1:8
New American Standard Bible
8 For the word of the Lord has sounded forth from you, not only in Macedonia and Achaia, but in every place the news of your faith toward God has gone out, so that we have no need to say anything.
( every place )
1 Corinthians 7:29-31
New American Standard Bible
29 But this I say, brothers, the time has been shortened, so that from now on those who have wives should be as though they had none; 30 and those who weep, as though they did not weep; and those who rejoice, as though they did not rejoice; and those who buy, as though they did not possess; 31 and those who use the world, as though they did not make full use of it; for the present form of this world is passing away.
Here Paul tells them to not focus on changing their status , because the time has been shortened and the world is passing away.
Itās at this point people begin to say ā but the world is the same. Itās not passed away. If this is the new earthā¦. Why is it like the old. They then think of verses around resurrection, eternal life, lion and lamb and so on. But thatās just symbolism. Itās hyperbolic. Just like the talk of endless fire, endless smoke and so on. Itās just end times and afterlife symbolism.
Insider Isaiah.
Isaiah 65:17-25
New American Standard Bible
New Heavens and a New Earth
17 āFor behold, I create new heavens and a new earth;
And the former things will not be remembered or come to mind.
18 But be glad and rejoice forever in what I create;
For behold, I create Jerusalem for rejoicing
And her people for gladness.
19 I will also rejoice in Jerusalem and be glad in My people;
And there will no longer be heard in her
The voice of weeping and the sound of crying.
20 No longer will there be in it an infant who lives only a few days,
Or an old person who does not live out his days;
For the youth will die at the age of a hundred,
And the one who does not reach the age of a hundred
Will be thought accursed.
21 They will build houses and inhabit them;
They will also plant vineyards and eat their fruit.
22 They will not build and another inhabit,
They will not plant and another eat;
For as the lifetime of a tree, so will be the days of My people,
And My chosen ones will fully enjoy the work of their hands.
23 They will not labor in vain,
Or give birth to children for disaster;
For they are the descendants of those blessed by the Lord,
And their descendants with them.
24 It will also come to pass that before they call, I will answer; while they are still speaking, I will listen. 25 The wolf and the lamb will graze together, and the lion will eat straw like the ox; and dust will be the serpentās food. They will do no evil or harm on all My holy mountain,ā says the Lord.
There it also mentions the new heaven and earth. It also mentions deaths, births and so on. Itās not literal and either is the verses in revelation about new heaven and earth. Itās all symbolism.