Here’s the peer-reviewed article. It appears in a scientific journal focused on astrophysics.

Here’s the abstract:

Both cosmology and philosophy trace their roots to the wonder felt by the ancient Greeks as they contemplated the universe. The ultimate question remains why the universe exists rather than nothing. This question led Leibniz to postulate the existence of a metaphysically necessary being, which he identified as God. Leibniz’s critics, however, disputed this identification, claiming that the space-time universe itself may be the metaphysically necessary being. The discovery during this century that the universe began to exist, however, calls into question the universe’s status as metaphysically necessary, since any necessary being must be eternal in its existence. Although various cosmogonic models claiming to avert the beginning of the universe predicted by the standard model have been and continue to be offered, no model involving an eternal universe has proved as plausible as the standard model. Unless we are to assert that the universe simply sprang into being uncaused out of nothing, we are thus led to Leibniz’s conclusion. Several objections to inferring a supernatural cause of the origin of the universe are considered and found to be unsound.

The whole article is posted online here.

Here’s an excerpt in which Craig explains the Big Bang cosmology:

The monumental significance of the Friedman-Lemaitre model lay in its historization of the universe. As one commentator has remarked, up to this time the idea of the expansion of the universe “was absolutely beyond comprehension. Throughout all of human history the universe was regarded as fixed and immutable and the idea that it might actually be changing was inconceivable.”{8} But if the Friedman-Lemaitre model were correct, the universe could no longer be adequately treated as a static entity existing, in effect, timelessly. Rather the universe has a history, and time will not be matter of indifference for our investigation of the cosmos. In 1929 Edwin Hubble’s measurements of the red-shift in the optical spectra of light from distant galaxies,{9} which was taken to indicate a universal recessional motion of the light sources in the line of sight, provided a dramatic verification of the Friedman-Lemaitre model. Incredibly, what Hubble had discovered was the isotropic expansion of the universe predicted by Friedman and Lemaitre. It marked a veritable turning point in the history of science. “Of all the great predictions that science has ever made over the centuries,” exclaims John Wheeler, “was there ever one greater than this, to predict, and predict correctly, and predict against all expectation a phenomenon so fantastic as the expansion of the universe?”{10}

As a GTR-based theory, the Friedman-Lemaitre model does not describe the expansion of the material content of the universe into a pre-existing, empty, Newtonian space, but rather the expansion of space itself. This has the astonishing implication that as one reverses the expansion and extrapolates back in time, space-time curvature becomes progressively greater until one finally arrives at a singular state at which space-time curvature becomes infinite. This state therefore constitutes an edge or boundary to space-time itself. P. C. W. Davies comments,

An initial cosmological singularity . . . forms a past temporal extremity to the universe. We cannot continue physical reasoning, or even the concept of spacetime, through such an extremity. . . . On this view the big bang represents the creation event; the creation not only of all the matter and energy in the universe, but also of spacetime itself.{11}

The popular expression “Big Bang,” originally a derisive term coined by Fred Hoyle to characterize the beginning of the universe predicted by the Friedman-Lemaitre model, is thus potentially misleading, since the expansion cannot be visualized from the outside (there being no “outside,” just as there is no “before” with respect to the Big Bang).{12}

The standard Big Bang model thus describes a universe which is not eternal in the past, but which came into being a finite time ago. Moreover,–and this deserves underscoring–the origin it posits is an absolute origin ex nihilo. For not only all matter and energy, but space and time themselves come into being at the initial cosmological singularity. As Barrow and Tipler emphasize, “At this singularity, space and time came into existence; literally nothing existed before the singularity, so, if the Universe originated at such a singularity, we would truly have a creation ex nihilo.“{13}

[…]On such a model the universe originates ex nihilo in the sense that at the initial singularity it is true that There is no earlier space-time point or it is false that Something existed prior to the singularity.

Now such a conclusion is profoundly disturbing for anyone who ponders it. For the question cannot be suppressed: Why does the universe exist rather than nothing? In light of the universe’s origin ex nihilo, one can no longer dismiss this question with a shrug and a slogan, “The universe is just there and that’s all.” For the universe is not “just there;” rather it came into being. The beginning of the universe discloses that the universe is not, as Hume thought, a necessarily existing being but is contingent in its existence. Philosophers analyzing the concept of necessary existence agree that the essential properties of any necessarily existing entity include its being eternal, uncaused, incorruptible, and indestructible{14}–for otherwise it would be capable of non-existence, which is self-contradictory. Thus, if the universe began to exist, its lacks at least one of the essential properties of necessary existence-eternality. Therefore, the reason for its existence cannot be immanent, but must in some mysterious way be ultra-mundane, or transcendent. Otherwise, one must say that the universe simply sprang into being uncaused out of absolutely nothing, which seems absurd. Sir Arthur Eddington, contemplating the beginning of the universe, opined that the expansion of the universe was so preposterous and incredible that “I feel almost an indignation that anyone should believe in it–except myself.”{15} He finally felt forced to conclude, “The beginning seems to present insuperable difficulties unless we agree to look on it as frankly supernatural.”{16}

I find that most scientists do not reflect philosophically upon the metaphysical implications of their theories. But, in the words of one astrophysical team, “The problem of the origin [of the universe] involves a certain metaphysical aspect which may be either appealing or revolting.”{17}

Every theist should able to understand and defend this argument. It is a scientific refutation of materialism, and it is supported by six lines of scientific evidence – all of which emerged as science has progressed.

Scientific evidence:

1. Einstein’s theory of general relativity (GTR)
2. the red-shifting of light from distant galaxies
3. the cosmic background radiation (which also disproves the oscillating model of the universe)
4. the second law of thermodynamics applied to star formation theory
5. hydrogen-helium abundance predictions
6. radioactive element abundance predictions

Those are the scientific discoveries that have led us to the beginning of the universe, which support’s Dr. Craig’s argument.

Several naturalistic/materialistic cosmologies are refuted in Craig’s peer-reviewed paper, including the steady-state model, oscillating model, the vacuum fluctuation model, the chaotic inflationary model, and the quantum gravity model. These naturalistic (no God) alternatives all have theoretical or observational difficulties. Atheism is at odds with modern cosmology – and the progress of science itself.

This is the kind of evidence I expect all my readers to be using when discussing whether God exists. Scientific evidence. When talking to non-Christians, it’s best to avoid quoting the Bible, talking about theology, or sharing our personal feelings and experiences. That can come much later when the person is open to it. We first need to show that we understand science, because science is a reliable and respected way of getting knowledge about the universe. Science (experimental, testable, repeatable science) should set limits on what anyone can believe – including non-Christians, who might otherwise not be inclined to listen to Bible verses and theology.

You should definitely print this article out and read it, then send it to your atheistic friends. I have tried this out on atheists, and the response I get is that scientific discoveries will soon emerge that falsifies all of these six scientific discoveries. That sounds more like faith than science to me. Let’s make the decisions based on what science is telling us today. Let’s not speculate against the science, let’s go with the flow of the recent discoveries.