Time is not an illusion. It is no more illusory than space is.

But it is also true, that you can never experience time directly. Whether you think of the past, or you think of the future, neither actually exist - these are just thoughts happening at the present moment. Notice that the same can be said about space - you perceive space, but you are always right here. But it doesn’t mean that it doesn’t exist. You can move in space and you’re constantly moving in time.

You could also look at the universe as one indivisible space-time object, and from that perspective, both past and future already exist, and your present moment and position is a dot moving along your individual trajectory. Saying that both past and future already exist and predetermined and saying neither exist are different ways of saying the same thing.

As far as spirituality is concerned, things get somewhat more complicated. The process of spiritual enlightenment is basically the process of moving towards imperceptibility of time. That’s why “time doesn’t exist” is such a well known spiritual cliché.

It starts with the realization that past and future are just thoughts, and they’re happening in the present. So first it is accepted that it is not possible to experience anything else other than the present moment.

Then psychological time starts to disappear. Psychological time is emotional time. It is based on the continuous re-living of your past emotional experience in form of memories and continuous projections into the future in form of expectations. It’s a story of your character, your persona, in which future is the past, re-imagined. As said persona starts to disappear and the emotional body dissolves, the sense of psychological time dissolves. It’s an emotional experience, and it’s scary. It often times feels like all time disappears, but it’s largely illusory. The collapse into the present moment continues.

Finally, at much deeper stages of the unfolding, the eternity is realized. It feels like deathlessness and it’s been described as such. It has also been described as transcendental awareness which exists completely outside of time, upon which time is but an illusion of the mind. This can only be realized upon true acceptance of death, entering Buddhahood, Shunyata. Because, strictly speaking, that’s what it is. It’s just the realization of death. Life cannot exist outside of time, but death is entirely outside of time. Life is finite, but death is eternal. Realizing your eternity and accepting your death is one and the same thing.

But ultimately even this awareness is temporary and illusory. There is no eternity, not here. You will die, but it’s not possible to experience eternity, so you might as well say you will never die, but it’s kinda silly to phrase it this way. What it means is simply that death cannot be experienced, it can only be made peace with, accepted. So, when the collapse into the present moment is complete, you still live in time. You do stuff, you age, and you ultimately die, just like everyone else. You’re just in a constant and never-ending peace with it, there’s no more fight left in you, just surrender and serenity, and life itself becomes the ultimate pleasure, the highest pleasure.

Death, when accepted, becomes like a deep sleep from which you never wake up. That’s eternity.