toxicTom: Does that mean there are things that begin to exists (have a cause) and things that exist without a beginning (without cause)? What is the logical premise for the uncaused type of existance?
If something has a cause, then its beginning was when it was caused. Something that is eternal doesn't have a beginning, so it is incoherent for it to be said to have a cause. If the universe is eternal, then it doesn't have a cause, but if it is finite, then it has a beginning and a cause. If there is being that caused the universe, then it could not be dependent on the universe for its existence, and thus must be beyond space and time, and therefore eternal. It is incoherent to ask what caused an eternal being.
1. Why does it have to be a single! sentient! being! in the first place? Why not some random natural effect? Why not multiple beings?
Edward Feser does a much better job explaining this than me, so I encourage you to read his book on Aquinas.
http://www.amazon.com/Aquinas-Beginners-Guide-Edward-Feser/dp/1851686908 Saying something is a being just means that it is something that exists. If this being doesn't have a cause, then it is not dependent on anything for its existence.
"There can only possible be one such being because it would be impossible in principle to distinguish more than one. We could not coherently appeal to some unique form one such thing has to distinguish it from others of its kind because then it would not simply be an act of existing, but an act of existing plus this certain form. Likewise, we could not associate it with some particular parcel of matter, because then it would not be subsistent existence, but material existence, and dependent on matter for its being." - Edward Feser
"As the cause of space and time, this cause must an uncaused, timeless, spaceless, and immaterial. The only two things that fit that description are abstract objects, like numbers, or an intelligent mind. Abstract objects can't cause anything, therefore this cause is a personal, transcendent mind.
How else could a timeless cause give rise to a temporal effect like the universe? If the cause were an impersonal set of necessary and sufficient conditions, then cause could never exist without its effect. If the cause were permanently present, then the effect would be permanently present as well. The only way for the cause to be timeless and the effect to begin in time is for the cause to be a person agent who freely chooses to create an effect in time without any antecedent determining conditions. Thus, is is not just the transcendent cause of the universe, but also its personal creator." - William Lane Craig
Maybe the Frnok grxbled the Tnistis in some previous or transcend universe and we simply can't know who or what Frnok and Tnistis are and how to grxbl, since they have no meaning in this universe?
If it turns out that there is some place else where the universe doesn't follow rules of logic, then I can correct my error and move on. But until then, I see no credible reason to take that into consideration. It is possible that this thing is the cause of Global Warming, but if you were to postulate it as the cause, scientists would consider you just as crazy and philosophers would.
2. Even if some timeless sentient being created the whole universe a few thousand billion years ago, why would it have any influence on our lives now? Why would someone assume to be personally watched and judged by it? On the scale of time and space of our universe the planet Earth and mankind are next to nothing.
3. Even if there was some single sentient being that created this universe and watched and waited for billions of years for sentient life to evolve - why would it reveal itself only to a rather minor tribe in a specific location of thousands of tribes and civilizations scattered around that fleck of dust in space we call home?
You're mixing up the argument for the classical God of theism with an argument for the God of Christianity. If it is an historical fact that Jesus rose from the dead, then this God would have the same identity as the Christian God, but even if Christianity is false, I think it is significant to prove the existence of the classical God of theism. If this God is the Christian God, then it should be believed that God did behave that way without necessary needing to know why we think God would.
The universe has a number of properties that appear to be finely tuned because if they were altered by just a fraction, the universe would not permit life to form. It is not a be a safe assumption to make that life would be possible to evolve in a smaller universe.
For me the first flawed assumption is that the universe was created with a purpose.
Nothing comes from non-being, so a random natural cause would still need an explanation for its existence.
The second flawed assumption is, that based on the first, mankind somehow is that purpose and the universe was created for it.
The third flawed assumption is, that if both are somehow true, my creation myth is somehow more true that the creation myths of other people - that I belong to the chosen ones that worship the true creator while the majority is wrong.
The fourth flaw is assuming that this omnipresent, omnipotent being that created a huge universe for the tiny humans cares for me personally.
Again, all of this again all of this is based on the particular identity of this being. If Jesus rose from the dead, the it validates his claims, so these things are not just assumed to be true.