In Islamic stories, we are told that Muhammad travelled from Mecca all the way to Jerusalem overnight by riding on a creature called al buraq. In modern times, of course all you need to get from Mecca to Jerusalem overnight is an aeroplane. So I note that with or without al buraq, we need another way of flying. Amongst other things, this 'democratises' such abilities. The problem with 'magic ways' is that they are often the privileges of a few 'select gurus'. In the era of al buraq, only Abraham, Moses, Jesus and Muhammad were privileged to 'fly'! But the same reasoning should be applied in any other thing that people desires, e.g. 'interstellar travel', 'living in a paradise' or even 'life after death'! We should try to achieve such things whether or not some deities etc have done it for us 'in ways that no man can understand'.
In the days of the bible's book of revelation, a floating city was 'beyond human ability' to even imagine. Amongst other things, it was seen that 'only God can hang things upon nothing'. So a city in the clouds could only be built by Jesus for over a period of 1000 years! However, in modern times, such cities in Jupiter and even pluto are within human imagination! Infact humans are now imagining that some ETs might have built a supercumputer the size of the sun! They are now looking for such objects in the skies. In other words we can now imagine doing things using science and technology that the ancient men did not imagine even using magics! We have imagined type 1,2,3&4 civilization, beginning with that one which will build a Dyson Sphere around a sun! Dyson sphere is a project several orders more monumental that building a floating, New Jerusalem as specified in the book of Revelation!
Think about a 'New Jerusalem-like city' near pluto 'floating away'. Indead it could, itself, be an interstellar space-ship, now heading to stars. It should be built in such a way that 'it will not need the light of the sun'! The concept of 'day and night' has no meaning in such a city, at such a distance away from the sun. Since it is into an interstellar journey, we must find a way of living for all that time. So there will be no death and hence no mourning in such a city. But if we can figure out how to dodge death during all that time, then we might have figured out the secret for immortality alltogether. All these without the need for gods!
The bible suggests that one way of lighting such a city is to let the people there glow in what the bible termed it as 'glory'! In those days, whence the best torch was just a burning substance soacked in olive oil or such, lighting a whole city without a 'sun' was inconceivable! So it neaded God to do that 'in ways that no man can understand'. But nowadays we can do that using the so called 'light emitting diodes' (LED). So all we need it to wear a musk full of tiny LEDs, so that our bodies looks like the smartphone screens! So the need for God to glow inside the city goes the way of the need for al buraq to take people from Mecca all the way to Iraq! We will do all these without necessarily insisting that there is no God, nor insisting that 'God is not necessary'. We will just change how we understand 'action of God in the universe' just like we do everything else. Christians donnot pray for God to take them from Japan to Cairo. Neither should they expect God to take them from earth to stars, hand them a floating city, or even a life after dead, if we can do these things ourselves! If we can do it, then hurrah!
Perhaps the most challenging part will be to figure out how to live after death! People have thought of interstellar travel but few see that perhaps immortality is a fleat we must first achieve before we can think of moving to stars! Since interstellar travel will be too long or too dangerous then rather than thinking of how to dodge all the dangers, we can simply think of how to 'resurrect' people should they die! We can think of how to make a body that does not feel pain etc. All these shows that the conditions described in Revelation, pertaining to the inhabitants of New Jerusalem are compatible to those who are inside a huge spaceship in an interstellar voyage! One way to dodge death is transference of consciousness into a clone. So we must change our attitudes towards the science of cloning. To suppose that 'it is wrong to clone a body' because 'it is like competing with God' is like saying that 'it is wrong for a muslim to make an aeroplane' because 'it is like trying to compete with al buraq'! If we entertain such, then we can dismiss any technology using the same logic. God has never said 'he doesn't want a competition from humans'. A being who fears competition is a limited one! Humans are the ones who hate a competitor. Shoving this to God as well is a dis-respect to God!
So yes, we can make 'Jerusalems', Souls, immortalities, al buraqs, living things etc even while God is seated somewhere and this will be a non-issue to God. God does not fear any competition from humans! Granted God might have made all these things for us, or for the saints. There might be a New Jerusalem and a life after death full of joy etc. But so might there be an al buraq! All you need to do, to get from places to places, is to be holy and then pray to God and then voila! A strange animal will appear before you and he will take you anywhere you want, from Jerusalem to stars! But does this mean we should not make aeroplanes or rockets etc?