In many traditional spiritualities time was regarded as flowing in cycles with a primeval Golden Age when man walks with the gods descending to a spiritually darkened time in which matter becomes more dense and impenetrable and consciousness collapses in on itself. Then the process concludes in cosmic destruction and a new era commences with another Golden Age.
Christianity rejected that idea, presenting a new understanding in which time progresses in a linear fashion from creation in the Garden of Eden leading eventually through a historical process to the city of the New Jerusalem in which creation is transformed and drawn up into divine reality.
Many people in the spiritual world nowadays reject the Christian view and prefer the cyclical one, seeing it as making more metaphysical sense. Strangely enough, one approach that roughly mirrors the Christian idea is the modern materialistic understanding of human life which would maintain we are progressing to a better human form in which science and technology correct all the faults of our physical bodies and give us, if not immortality, at least a more perfect vehicle to house our consciousness which will also be tweaked and improved though technological means whether that be drugs or even by blending us with machines. This is transhumanism, a great spiritual evil because it denies the spirit replacing it entirely with matter, but one to which the modern world seems inevitably to be tending.
Which of these two ideas about time is the more accurate? My answer is that both are true. Time is indeed cyclical but it also moves forward and if there is a spiritual descent the purpose of that is to bring about conditions in which consciousness can become more individualised with a greater sense of personal freedom in the constricted material conditions. Then there can be a reascent but with the fruits of greater self-awareness.
Most people interested in traditionalist metaphysics believe that all religions convey the same essential truths. There is a perennial philosophy which is the root of them all and they differ only in externals and certain relatively unimportant doctrines. I think this is a mistake. There is something qualitatively different about Christianity and what Christ brought to human consciousness. It has to do with freedom, it has to do with love and it has to do with time. In traditional metaphysics time is something to be transcended. One goes beyond all aspects of the material to enter into complete spiritual consciousness. But Christ redeemed creation which means the qualities of the relative world are not completely transcended and effectively lost but they are spiritualised and thereby add something to divine reality, something that was not there before.
Time is certainly a great mystery in that there is a state beyond earthly time which is the state of divine being. But it is not simply an illusion from the spiritual point of view. It is not just swallowed up in eternity. Through time creation is brought to fulfilment but then at the end of worldly time something happens that is similar to what happened to Christ's body at the Ascension. Time will be taken up into eternity but it will thereby enrich eternity, its quality sweetening eternity as sugar when dissolved sweetens tea.