A popular objection to the second premise of the Kalam Cosmological argument (“the universe began to exist”) is that the universe is eternal. This objection asserts that the universe existed infinitely in the past. If this objection were true, it would be very effective against the Kalam. For, if the universe is eternal and never began to exist what need is there for God? Famed cosmologist and atheist, Sean Carroll, has said:
Most modern cosmologists are convinced that conventional scientific progress will ultimately result in a self-contained understanding of the origin and evolution of the universe, without the need to invoke God…. If we are able to construct a complete and compelling naturalistic account the necessity of appealing to God would be diminished. A number of avenues towards this goal are being explored. They can be divided into two types: ‘beginning’ cosmologies, in which there is a first moment of time, and ‘eternal’ cosmologies where time stretches to the past without limit.
There are two problems with the eternal universe position: 1. Science denies it; and, 2. Reason denies it.
- Science denies that the universe existed eternally in the past. This is confirmed by modern cosmology. Alex Vilenkin, a cosmologist at Tufts University writes,
The key insight of my paper with Borde and Guth is that as we go into the past and approach past infinity by the clocks of the spectator, the time elapsed by the clock of the space traveler is still finite…his clock essentially comes to a halt…the space traveler’s history should extend into the past…the conclusion is that past-eternal inflation without a beginning is impossible.
Vilenkin goes on to say,
It is said that an argument is what convinces reasonable men and a proof is what it takes to convince even an unreasonable man. With the proof now in place, cosmologists can no longer hide behind the possibility of a past-eternal universe. There is no escape; they have to face the problem of a cosmic beginning. 
- Reason denies that the universe existed eternally in the past. Focusing on the second possibility mentioned by Carroll (an eternal universe), the question is, if the universe has been around for an infinite amount of time, how could we ever arrive at “today?” In other words, the eternal universe claim produces a paradox – because prior to “today” there was an infinite number of days, but if there was an infinite number of days prior to today, we could never arrive at today. Yet “today” has arrived! This paradox suggests that the universe did not exist eternally in the past. Moreland writes:
...the present moment has as its ultimate chain of causal antecedents the entire history of the cosmos. If any past event has not already been actualized, then the present moment could not have occurred. This means that the past is actual and contains a specifiable, determinate number of events. This chain of events must have had a first member. Without a first member, there could be no second, third, or nth member in the chain where the nth member is the present event. But an infinite succession of past events would not have a determinate number of members nor would it have a first member. So if the past is actually infinite, the present moment could not have been caused; that is, it could not have come to be.
Consequently, many philosophers working on the question of infinity conclude as David Hilbert (possibly the greatest mathematician ever) has that “the infinite is nowhere to be found in reality. It neither exists in nature nor provides a legitimate basis for rational thought…the role that remains for the infinite to play is solely that of an idea."
So, while “to infinity and beyond” may be a great slogan for a series of animated children’s movies, it seems that toying with the universe being past eternal is simply not the story of our universe’s existence. It is not infinitely old, therefore, it must have a cause.
 See S.M. Carroll (2005), “Why (Almost All) Cosmologists Are Atheists,” Faith and Philosophy 22, p. 622. For a different view, see D. Page (2008), “Does God So Love the Multiverse?” http://arxiv.org/abs/0801.0246.
 Alex Vilenkin, Many Worlds in One: The Search for Other universes. (New York: Hill and Wang, 2006) 175.
 Ibid., 176.
 Moreland, “The Kalam Cosmological Argument”, p. 201.
 David Hilbert, “On the Infinite.” Philosophical Mathematics (Englewood Cliffs: Prentice-Hall, 1964), 141