Big Bang to God

P1. Whatever begins to exist cannot come from nothing.
P2. An eternal universe is illogical (entropy > heat death, infinite regress. See "A." below for further explanation)
C1. The universe (time, space, energy included as the time-space continuum) has a beginning.
P3. Einstein showed that time, space, and energy are co-relative which means all 3 must exist simultaneously or none do.
C2. Therefore, the universe (time, space, energy) has a cause.
C3. Therefore, since X cannot cause X (Principle of Causal Priority) the cause of the universe is timeless, spaceless and immaterial (and so needs no beginning, this is the uncaused cause)
P4. the uncaused cause/first cause, must be the explanation for all caused things (reality)
P5. to cause something means to bring something from a state of non-being (non-existence/what it is not/potentiality) into a state of being (existence/what it is/actuality) or more specifically in reference to contingency/dependancy, which potentiality implies. (See "B." below for definitions)
C4. Therefore, an uncaused being cannot have any unrealized potential—otherwise it would be dependant on a cause to actualize it. The uncaused cause must be pure actuality: fully real, with no possibility of growth or change. (See "C" below for a full breakdown)
C5. pure actuality implies maximal being (encompassing all things) which among other things means Omnipotent, Omniscient, Omnipresent, Omnibelevolent, etc (See "D." below if unclear)
C6. this lines up with the definition of god in classical theism.
P6. A contingent being cannot explain its own existence, nor can a series of contingent beings (even infinitely many).
C7. Therefore, only a necessary being (pure actuality) can ground the existence of contingent beings.

A.
One of the consequences of entropy is that as energy is transferred (which is not 100% accurately) some is converted to heat, friction, etc or lost due to fighting against air resistance. Entropy is a measure of a systems thermal energy or rather the unavailability of it. on other words as time goes on, the energy that has been converted to thermal energy will grow over time and become unavailable for more work, This is the very foundation of heat death (which is very widely accepted). Now heat death will occur in some finite amount of time let's call this amount of time "X" (I think 1-100 trillion years or something) but if the universe is eternal or in otherwords t = ∞, then for all real numbers X, ∞ > X, or in otherwords infinity is bigger than any finite amount of time. So if the universe is eternal, heat death should have already occurred (but it hasn't) this means that either: heat death must be impossible (which means that entropy must not exist or there is some magical way to generate energy, which violates multiple laws of physics and is basically saying that the universe is a perpetual motion machine) OR the universe cannot be eternal.

second problem is that of infinite regress, luckily this is alot simpler to grasp. infinite regression means the chain of causes in the universe would span back infinitely (which would be the case if the universe is eternal) let's analogize this to beliefs let's say that everything we belief is because of some prior belief, so we believe A because of B, we believe B because of C, C because of D, etc
if this series is infinite then there cannot be a first belief to justify any of this beliefs and if there is a first belief the series simply isnt infinite but finite. just like the universe if it is an infinite series there is no starting point and so no ultimate foundation for anything to exist at all not even you or I.

B.
potentiality
/pəˌtɛnʃɪˈalɪti/
noun
1.
The inherent capacity or possibility within a thing to change, develop, or be actualized by something else.
"the marble has the potentiality to become a statue when acted upon by a sculptor"
2.
The state of being incomplete or unrealized, awaiting fulfillment by an external cause.
"every created thing exists with some potentiality that only actuality can fulfill"

actuality
/ˈaktʃʊˌalɪti/
noun
1.
The realized state of being; the fulfillment or completion of potentiality.
"the statue is the actuality of what the marble was in potentiality"
2.
The condition of existence or being in act, especially in contrast to mere possibility.
"movement is the transition from potentiality to actuality"

C.
The principle behind C4 rests on the relationship between potentiality and actuality. When we say something is caused, we mean it began to exist — it moved from a state of potentiality (not-yet-actualized existence) to actuality (fully real existence). in other words it goes from what it is not (in potentiality) to what it now is (the actualized potential)
Formally, we can represent this as:
C ↔ (P ∧ A)
“Something is caused (C) if and only if it has both potentiality (P) and actuality (A).”

Potentiality means it can become or change into something actual (by another thing that is actual).
Actuality means it exists with some properties.

Negate both sides (contrapositive)
∼C ↔ ∼(P ∧ A)
"The thing is uncaused iff it is not both potential and actual."
which by De Morgan’s law becomes:
∼C ↔ (∼P ∨ ∼A)
“An uncaused thing either lacks potentiality OR lacks actuality.”

However, actuality (A) is necessary for existence itself — to be “not actual” would be to not exist at all, which violates the principle that something cannot come from nothing (P1). Thus,
∼A is impossible.

Given that, the uncaused cause cannot lack actuality, it must lack potentiality:
∼C ↔ ∼P

This means that the uncaused cause is pure actuality — it has no potential to become something else because it is already fully actualized existence. It is the fullness of being itself, without any possibility of non-existence or change. Thus,
∼C → A

D.
If C4 and C5 are still hard to grasp, consider this: imagine that nothing exists except one single being—call it B. If this being is truly maximal, it means it includes everything that exists or could exist within itself. In other words, there is nothing outside or beyond this being.

Now, if there were something else outside of B, something independent or separate from it. Then B would not be maximal, because its existence would be limited or incomplete. To truly be maximal, B must encompass all things, leaving no room for anything else outside of it.

If something else did exist beyond B, that “something else” would have to be more fundamental or more real than B, which contradicts B being maximal. This pushes the argument back to require a maximal being that fully grounds and encompasses all contingent realities (which in this case would include B).

This is supported by the principles of Metaphysical Dependency and Causal Priority, which say that dependent or caused things rely on a more fundamental, independent cause or being. That fundamental being, which must be pure actuality (lacking any potentiality), is the ultimate source of all existence and unbounded from any properties (timeless, spaceless, immaterial) and maximal (Omnipotent, Omniscient, Omnipresent, Omnibenevolent).