This is called Tie-breaker because it moves us past the log jam that results in saying God is uncased and timeless always has been always will be with cause, vs. the atheist argument that this is no better than just saying the universe happens to be here for no reason. My friend Eric Sotnak, who has a great gift for sarcasm that is not lost on me, set's it up as a matter of brute facts. There is a huge literature on brute facts but I wont go into it because I don't have time and I'm no expert. A brute fact is a thing that exists for no higher purpose, it has no reason for being it just is.  Now some will argue that brute facts can have physical causes or not. Since we have no examples of anything in nature that has no cause that just leaves and the universe as a whole. So the comparison between atheism and theism is between God who has no cause vs a universe that has no reason for being weather it has a physical cause o not Having no reason means it could as easily not be. Sotnak turns this into an argument agaisnt the existence of God, but couches it in terms of God as a brute fact:
Traditionally, theists have felt extremely uncomfortable with the idea of a “brute fact” – that something could have just happened without explanation. Instead, they have committed to variations on the Principle of Sufficient Reason (PSR).I think the main reason for this is that they know quite well that without PSR, they will have no way to rule out the hypothesis that maybe the universe is just a brute fact (no God required).But I think theists could comfort themselves a bit by shedding their anxiety about this. Imagine a conversation like this between a theist (T) and an atheist (A):
A: I think the universe is a brute fact.T: Not I. I think it was made by God.A: But then where did God come from?T: God is an eternal brute fact.A: How does that make you better off than me, then?T: Well, while no logical proof of God’s existence is possible, I have subjective or existential reasons for being a theist. It seems to me that I can feel the presence of God in the laughter of my children, for instance. For me, theism helps me to make sense of the world and comforts me with the hope that death isn’t final.A: But if God is a brute fact, that means he could, logically speaking, have failed to exist.T: Yup. So I feel extra lucky that he does.Since God cannot fail to exist (definition of necessary),that is an intrinsic part of the definition of God; then to say God is a BF in this sense is to say there is no God. One might believe in a demoted god who is not the God but a sort of very power strange being we don't know about. Zeus or something. This is why we need a tie breaker because there is a supposed tie between God as BF and the Universe as BF. God cam't be abrute fact and still be God in the Christian sense. Yet there is this seeming tie between un-caused God and uncaused universe. We have to do this in such a way that the universe can't be withouut a cause and God who has no cause cannot be a brute fact.
To break the tie we just need to distinguish between the two kinds of un-caused nature. The argument is going to turn-on the concept of a BF. The nature of God's un-caused state is not the same as the nature of BF. To be a BF a thing must have no connection to a higher purpose. God can't have a purpose higher than himself but he can have a purpose higher than mere brute facticity. Semantically the two are different, Brute facts have higher purpose, God has asaiety not brute facticity. That it is part of the definition of what God is that he eternal and necessary. It's not part of the definition of the universe that it exists. That's existence as a predicate. On that basis Bertrand Russell ruled out the ontological argument. Existence is not a quality to be defined as part of the object, "I have one of those brick houses it;s the kind that exists." That goes beyond the semantic aspect and it can be understood in terms of the nature of being.
God is being itself of the ground of being. The universe is not the ground of being. Even if it has no cause and has always existed the universe cannot be called the ground of being without attaching to it some higher sense of special nature such that we can think of it ass "holy being." But before we do deifying the universe there is no reason to assume that the universe is eternal or uncased. If it was, if we could call it God there would be a God and atheists would be wrong , even if Christians were wrong too. We can eliminate that possibility. We know the universe is not eternal  and It did not pop out of nothing. The rea contest is between a meaningless accident that somehow came to be for no reason with no higher purpose ,which we call "the universe" vs. the ground of being or holy being which eternal, necessary (could not have failed to exist) and eternal cohere's within the infinite folds of a core purpose upon which the all existence coheres. That is not purpose higher than itself but is it;'s own purpose (that the universe doesn't have).
Now I hear the question "so what is God's big purpose?" God is not just being itself but as such is being por soir. Jean-Paul Sartre's term meaning being for itself. The alternative is being in itself. (en soir). In itself is inanimate (universe) and for itself is conscious and purpose; the purpose is set by God's nature which is love. Love is the will to the good of the other. Being for itself means it has will, volition and purpose. That purpose is to love to create more being and to provide for the good of such being. That is going to open a lot questions about the nature of life and theodicy, that has to wait for another time, This breaks the tie because it gives God a purpose, self authorized, which the BF doesn't have.
a couple of notes on Eric's dialogue:
A: I think the universe is a brute fact.T: Not I. I think it was made by God.A: But then where did God come from?T: God is an eternal brute fact.
No that is the wrong answer. He misidentifies aseity as brute fact which it is not. God has a purpose and is self perpetuated, the universe has no purpose and is not perpetuating itself. It has nothing to do with its own existence. Now we come to Eric's real gift of sarcasm:
T: Well, while no logical proof of God’s existence is possible, I have subjective or existential reasons for being a theist. It seems to me that I can feel the presence of God in the laughter of my children, for instance. For me, theism helps me to make sense of the world and comforts me with the hope that death isn’t final.That's mockery of mystical experience, Yes God ks beyond our understanding, All the things we say about god are either very limited or metaphorical. The fact is the life transformation chances are proven fact established by 200 or more empirical scientific studies in peer reviewed journals. For more on this see my book The Trace of God by Joseph Hinman, on amazon.
A: But if God is a brute fact, that means he could, logically speaking, have failed to exist.T: Yup. So I feel extra lucky that he does.
That would be a conceptual contradiction at the heart of the God concept, thus no God. Such is not the case.
 There's a problem with the definition of a brute fact. Different philosophers have different definitions. Atheist from is at work. the definition is changed from the way I learned it (no reason for being) to a definition that has to include god (something we can't explain)I disagree, I don't that as a BF. God being beyond understanding and explainable for that reason is totally different than saying "X just just happens to be for no reason." The chief difference is for the one the could be a reason we just don't understand it,for the other there is none, The fact of a purpose involved with God as being i think breaks the tie
 Ground of being is a concept made famous by Paul Tillich and other theologians, I've written about it vociferously. It basically amounts to saying God is the basis of reality. My A"Introduction to Paul Tillich's Existential Ontology" Metacrock's Blog http://metacrock.blogspot.com/2010/02/introduction-to-paul-tillichs.html
 Quentin Smith, “The Uncased Beginning of the Universe.” The British Journal of the Philosophy of Science, (1988, Vol., 55, no. 1), 39-57.
 Joseph Hinman, "Quantum Particles Do not prove universe from Nothing," The religious a priori, website URL: http://religiousapriori.blogspot.com/2016/03/quantum-particles-do-not-prove-universe.html
 Joseph Hinman, The Trace of God:Rational Warrant for Belief. Colorado Springs:Grand Vidaduct, 2014.