Hello, first I want to apologize if I write something that you don't understand, but I don't speak English as my main language. I'll try to put this the best that I can:

This is a question to anyone with knowledge from physical laws, Relativity, Quantum Physics and so. I'll also put some questions to theists that base their belief in a Creator God, that is, a cause without cause.

1. Thermodynamic laws says: No matter or energy can be created from nothing but they may change from one to another. As I understand there are four transformation allowed:

Matter->Matter
Energy->Energy
Matter->Energy
Energy->Matter (I'm not sure about this)

So the Big Bang did not create anything, it just changed how things were disposed (how matter and energy were displaced in space and time). So, assuming it happened 15 billion years ago (or whenever it may have happened), Why did the matter and energy contained in the primitive universe need to be created at all? Why it cannot exist since forever based on that law?

2. Assuming the Big Bang in fact did create something: It created time. Isn't it absurd to question what was "before" the time itself? Since before and after are words that needs time to have a meaning.

3. Just today I've read an interesting theory in slashdot: Gravity curves time/space making time to be slower while greater the gravity is. That way, making a graphical time speed/gravity representation, time speed will tend asymptotically to zero as gravity grows to infinity (I've read before somewhere that time decelerates considerably in black holes). Assuming that all matter was concentrated in a point in the Big Bang and that gravity was inconceivably great in that point, couldn't it be that time speed was zero until the Big Bang instant? That goes to hypothesis 1: Time, space, matter and energy existed before the Big Bang (if it has any meaning) but just as time did literally not "pass" it was just like a photo. It has no "begining" because time speed before the Big Bang was zero (or almost equal to zero and decreasing as we go to the past).

What do you think of the three hypotheses? Could they be wrong? I'm not physicist and I don't have the needed knowledge about Relativity or Quantum Physics, just the things that I learned in school and the University and they were most classical physics.

And to theists: If someone doesn't correct this theories as wrong, how do you justify the existence of God as the Prime Creator based on causality since causality needs time to be considered?

Conservation of energy means that the amount of energy, impulse does not change. In General relativity this might be a little different/more complicated. In that case conservation is true for flat space, but i am not sure about arbitrary spacetimes.
Thermodynamics itself is much more tricky, things in it really are not as undisputable as people claim it is.(just had a course about that)

The A->B's of your post is from the physics point of view, silly. There is not something as energy that is nothing else(like matter) just as there not something like impulse that is not something else.
Perhaps if people say that they mean radiation-like and matter-like, in which the latter refers to relativistic speeds. But mostly if someone says something like 'pure energy' he is just spouting out nonsense.

(2) I do not know exactly, have followed general relativity.(did not pass ) But i did not see a treatment of that, specifically. I could look at a solution for a expanding universe, but i am not sure it will answer anything. It will give aspects on the event, but not near t=0, since quantum has to be accounted too there, and we do not have sufficient theory of both. Maybe in a philosophy of science course i will learn more on that.

(3) Physicists might say stuff like that, but that is not how to argue, it is not sufficient to talk just about 'speeds of time', when space is curved like that. Also, to talk about anything in physics, one has to turn to the math.
Also other coordinate systems might not respect our ideas of time!

Note that time is more complex then how you are thinking about it, it is a dimension, just like the spatial ones. It is only because of the situation of space-time that this dimension 'behaves differently'. The origin of this different behavior stems from the(approximate) rotation symmetry of the universe, on the spatial coordinates. (probably mirror symmetries of spatial coordinates is enough for it, not sure)
Then there is the "arrow of time"; all the fundamental physical laws of nature are time-reversal invariant!! (and those that are not are phenomenological) Then why does a cube of ice melt, rather then that water mysteriously turns up cubes of ice! This is a mostly unresolved question of thermodynamics and statistical dynamics.

Edit: Note that i am just a physics student who hopes to get his bachelor this year.