OK, after rereading the thread, I think we may need to discuss time a little more carefully, especially why the comparison between the number line and time is valid. (This seems to have been a sticking point for RGCheek.

)
In reality, this is a very old problem, which has its roots in the famous paradoxes of Zeno, in which the philosopher attempts to disprove the reality of both multiplicity and movement.
The most pertinent one is the paradox of the arrow: we are to imagine an arrow being shot. It appears to be moving, says Zeno; however if we were to examine it at any given infinitesimal moment–if we could stop the videotape, so to speak–it would actually be stationary. Therefore, argues Zeno, in reality the arrow is stationary at every moment. (Millennia later, Immanuel Kant thought up a strikingly similar “antinomy of pure reason” which, I think, can be answered in a similar fashion.)
I think that Aristotle’s reply is the best one: he notes that there is a qualitative difference between an arrow in motion and an arrow at rest. (I concede that rest and motion are, as Newton noted, relative to the observer, but the fact of the matter is, you have to get out of the way from an arrow being shot at you, not for one sitting on the ground.) In fact, a flying arrow is in the process of completing a movement: as such, that movement is partly complete, partly incomplete. (In Aristotelian language, it is partly
in act and partly
in potency.)
Zeno’s error, argues Aristotle, is envisioning time (and space) as a succession of infinitesimal discrete “points,” ignoring the fact that a flying arrow possesses a quality (a certain velocity) that the arrow at rest does not. (Or taking into account Newtonian mechanics, they have, in any case, different velocities.)
Time, says Aristotle, is intimately connected with changes (or “motion” as he calls it). If there were no changes whatsoever (as Zeno thought), there would be no time. It is this connection with change (or motion) that gives time its directional character: strictly speaking, only the present actually “exists;” it is impossible to make the past return or the future appear.
Material things constantly perform actions, bringing them to completion (in Aristotelian parlance, they go from
potency–an incomplete state–to
act–a complete state): acorns germinate and become oak trees, arrows fly, stones fall to the earth, the sun rises and sets (or, as we now know, the earth rotates, making the sun appear to rise and set), and so on.
Time is not identical to these changes, but is their measure. How do we know how “long” something takes? Only by comparing it to how “long” some other, relatively stable change takes (whether that be the rising and setting of the sun, the hands on a watch, or the natural oscillations of Cesium-133).
So, returning to our problem, “time” exists only to the degree that there is observable change (or motion), and it is the directionality of motion (the fact that it always goes from incomplete to complete) that gives time its directionality.
There is, however, nothing preventing these motions from always having existed or existing forever in the future (except for the fact that God decided to create things the way He did: with a temporal beginning and end). Naturally, that would take nothing away from God as Creator: in such a hypothesis, he would have created an infinite succession (but not a
regression, not in the sense that Aristotle talks about it), but created it, nevertheless.