The Kalam Cosmological Argument presents an argument for the existence of God from the existence of the universe by posing a series of three dilemmas, each of which builds upon the other. The three dilemmas are as follows:
(1) The universe had a beginning or it did not have a beginning.
(2) The beginning of the universe was caused or it was not caused.
(3) The cause of the universe was personal or it was impersonal.
The three dilemmas present the three questions in "A or not-A" styles. Thus, it is not possible to choose some other intermediate ground on these issues. Either the universe had a beginning or it didn't -- there is no middle ground. It is only if the question is answered in the affirmative that one would move on to the second question.
I think that most people now acknowledge that the universe had a beginning. While there remain models for a beginningless universe, most scientists that I have read seems to agree that the universe is expanding and it is accelerating in its expansion. Thus, the evidence suggests that it started from a single point and will expand eternally. In other words, there was a beginning and it wasn't part of a repetitive cycle of universes. So, most people will agree with the fact that the universe had a beginning.
It is the second leg where people get hung up. They agree that in the ordinary course, events do not happen without a cause. Thus, in the ordinary case they would acknowledge that if a boulder falls, it fell because of gravity. But they are willing to point to an exception: quantum mechanics. Hearing that in the wild, wacky quantum universe particles seem to explode into our universe as if they appear out of nothing, people assume that the universe could have come into existence in the same way as these subatomic particles, i.e., simply appear out of nothing.
But it is my understanding that scientists don't believe that these particles come into existence out of nothing. Keep in mind, quantum mechanics is a developing, inexact science which deals with particles much too small to measure (in fact, one of the problems of quantum mechanics is that you cannot measure these particles because the method used for measuring changes the particles' attributes). Thus, what scientists in this area are saying is that these particles "appear to come into existence without cause," but that is by no means a final answer or even certain. In other words, it is not by any means certain that these quantum particles are coming into existence "uncaused" in any ordinary sense of the word. They may simply be stepping into and outside of our ability to sense of measure them. This action of moving from one place to another outside of our ability to measure, to my understanding, is "quantum tunneling".
Some suggest that the universe came into existence as the result of "quantum tunneling." Dr. Hugh Ross has responded to that claim in an essay entitled "Quantum Mechanics, a Modern Goliath" where he notes:
Noting that virtual particles can pop into existence from nothingness through quantum tunneling, [British astrophysicist Paul] Davies employs the new grand unified theories to suggest that in the same manner the whole universe popped into existence. Ironically, his argument against God's creating can now be turned against his hypothesis. Quantum mechanics is founded on the concept that quantum events occur according to finite probabilities within finite time intervals. The larger the time interval, the greater the probability that a quantum event will occur. Outside of time, however, no quantum event is possible. Therefore, the origin of time (coincident with that of space, matter, and energy) eliminates quantum tunneling as "creator."
To Davies' credit, he has been revising his position. He recently argued that the laws of physics "seem themselves to be the product of exceedingly ingenious design." Still more recently he posed this question: "If new organizational levels just pop into existence for no reason, why do we see such an orderly progression in the universe from featureless origin to rich diversity?" He concludes that we have "powerful evidence that there is 'something going on' behind it all."
In other words, if a person argues that the universe sprang into existence from nothing based on quantum mechanics, it appears that it is appropriate to note a couple of things: first, these particles aren't necessarily popping into existence, but merely moving from a place where they can't be detected to a place they can. Second, these quantum activities are taking place in a universe where time exists, and if time didn't exist, these activities couldn't happen. Since time came into existence with the universe, how did these quantum events occur when time didn't exist?
Can quantum tunneling explain the universe? Well, it might, but at the moment I have no compelling reason to believe that it does.
Anyway, once you get them to see that the universe as we know it is a chain of causation, ask them why it should come into existence from nothing and without cause. Why should that change. Also, it is not meaningless to speak of "before the universe came to be" because of the nature of the universe. We know that there was a time that the universe came to be, approximately 13 billion years ago. 20 billion years ago, there wasn't a universe. There may not even have been time, but there certainly wasn't a universe. Now in this state of "non-time" before existence, what made the universe spring into existence from the three choices I described, i.e., nothing, laws of nature (which weren't in existence) or intelligent cause?