J. Preston Eby said:
A concept we must immediately grasp in order to understand God's plan of the ages is that time is a created phenomena consisting of past, present, and future just as man is created phenomena having youth, middle age, and old age. No, you cannot smell, touch, or feel time, but it is there, ever-present, always marching into the future. Time was created; it had a beginning, it shall have an end. It is only one thing among countless other things that are part of the entire created universe. It is as much a "species" of creation as, for example, rocks, elephants, trees, and water are species of creation. Before the creation of the universe, there was no time; at the end of the ages when the present material universe is dissolved and replaced by a new, spiritual universe, time shall cease to be. It will be swallowed up into eternity just as all death will be swallowed up into victory, and there shall be no more death. Time - composed of milliseconds, seconds, minutes, hours, days, weeks, months, years, decades, centuries, milleniums, ages was created in the beginning, and will be dissolved at the end of the ages.
A proper understanding of time as a created phenomena having beginning and ending is an absolute prerequisite to a proper understanding of eternity. Time is relative only to the physical universe and the purposes of God therein. Let me ask - If there were no such thing as the planet earth, would there be days? No! If earth didn't have a satellite called the moon, would there be months? No! If both earth and moon didn't have a thing called the sun around which to orbit, would there be years? No! If there were no stars, no suns, no planets, would there be time? No! Time is "duration set forth by measures;" the ticking of a clock, the beating of a pulse, the burning of a candle, the falling of sand through a certain aperture, - these, and a thousand similar regular movements, may serve as measures, more or less exact, of time. Time, then, because it is a created phenomena, can be studied to some extent just as any other part of the creation of God can be studied. We know how it functions by its effects in passing: decay, corrosion, erosion, deterioration, or progression, growth, development, maturity.
The late Dr. Einstein discovered, at least theoretically, that time and space are interdependent, inseparably related, and form a four-dimensional continuum (length, height, depth, and duration). That is to say, there is no space without time, and no time without space. Space cannot be traversed without the passage of time; without the passage of time, there is no traversing of space. That is why in His post-resurrection, spiritual body, Jesus was able immediately to transcend and traverse the space-time continuum with the speed of thought. By Christ's power, space and time cohere and consist. Without His binding power, space and time would become nonexistent. Also, since we know from the Scriptures that space is created, we can then know that time is created, too. We can also understand that both time and space (as we presently know them) will end together at the conclusion of the ages.
I am compelled to state that the Bible says very little by way of a definition of eternity because the Bible is essentially a book of time and for time. It was written for man who lives in a temporal state and who is not yet a totally eternal being. Only as we enter that state of being called eternity... only as HE who is eternity becomes "All in All" in us... only as we are spiritually metamorphosized into our eternal condition... only as eternity becomes an absolute reality to us... only then will formerly temporal beings such as we now are truly comprehend and understand eternity and things of an eternal nature. This marvelous work has now begun within our spirit as our spirit has been quickened by His Spirit. I stated that the Bible is relatively silent about what eternity is; that is not to say that human teachings and theology haven't taught us a great deal about eternity, but, alas! much of it over the past centuries has come from the carnal minds of Babylonish theologians and not from the mind of the Eternal One via the Holy Spirit.
Eternity is a state of absolute timelessness, not of unending time. Eternity is a state of being, resident in the very nature and person of God in which such concepts as past, present, future, before, after, change, transition, growth, decay, etc. do not exist. It is wrong to assert that, when time ends, eternity will begin, because eternity has no beginning. Neither did it end when time began, as so many charts indicate.
Therefore it is very important that we make a clear distinction between ages, which belong to time, and eternity, which is timeless. It is more important still that we, in our study of the Bible, search out diligently those passages which refer to time and those which refer to eternity. Do you have it yet? Do you see? Time is not part of eternity; eternity is not composed of segments of time. Eternity is not time standing still; it is simply not time at all. Eternity doesn't go on and on and on, ad infinitum. Eternity doesn't go anywhere, nor does it do anything. Eternity simply is. Eternity is part of the very nature and person of God. Eternity transcends beyond our knowing anything having to do with time. It is not time at all. It is just a glorious experience of being! Eternity simply is, just as God simply is. Jesus said, "Before Abraham was, I AM" (Jn. 8:58) - not "Before Abraham was, I WAS." There are not past or future tenses in eternity. There is only one eternal NOW.