1 Is God the only uncaused cause in existence?
That is the Kalam Cosmological Argument, and it has been thoroughly debunked. The argument is as follows:
"Everything that has a beginning of its existence has a cause of its existence.
The universe has a beginning of its existence.
Therefore:
The universe has a cause of its existence.
If the universe has a cause of its existence then that cause is God, who does not have a cause."
The first problem is that it is contradictory. "Everything has a cause... except for one thing that caused everything else. That one thing didn't need a cause."
Other problems include:
1. Quantum Mechanics has proven that something does not need a cause. Therefore, the premise of the argument is false.
2. Infinite regression is possible. Something does not 'need' a beginning. That part of the argument is also false.
3. There is no evidence for such a supposition, and therefore no reason to conclude that it is true.
4. Even if we pretend that the premises are true, the argument does not prove that the supposed creator is/was a specific god from a specific denomination. The creator could be a god that's no longer worshiped. Or multiple gods. Or aliens. They all have the same amount of empirical evidence (none). Therefore, the KCA a non-sequitor (means 'it does not follow,' a logical fallacy).
2 If 1 is true then what was the cause of vanity, disobedience, pride and all of the other things said to have been inherent in man?
The result of the Fall of Man/Satan is the typical answer. *shrugs*
3 If there is an adversarial force to God why was it able to become that way?
In the Bible, God outright states that he created evil (obviously, since he supposedly created everything, including the tree and Satan and all that stuff), so this begs another question; how can a supposedly perfect being be the root of all evil? Beats me.
But if you're talking about the Castlevania-verse, who knows. As far as I know, there is no basis for why Celia/Alucard said that there must be something in opposition to God. I could try and figure out where that came from, but I don't know if there's anything to find.
4 If God is all loving and does not change i.e. is the same yesterday today and tomorrow where did this angry God come in?
Someone might claim that:
* God has always been good; he is so good that he cannot tolerate even the slightest sin, and is therefore perfectly justified in being angry. And God did not change. He merely created a loophole through Jesus Christ by which we imperfect, unworthy humans may avoid the consequences of God's intolerance of sin.
* It isn't your place to judge God.
* God is allowed to change his mind depending upon the circumstance.
Etc...
More interesting questions that you can pose are:
1. How can imperfection spring from a perfect creator?
2. How can free will exist if a being can know everything? How can free will exist in a world that operates on cause and effect? If it cannot, then why would a system of eternal reward/punishment be in place?
3. How do we tell the difference between the work of one creator and the work of many creators? How do we determine which religion is correct if they all have the same amount of empirical evidence supporting them?