Leibniz's Argument:
1.Everything that exists has an explanation for its existence.
2. If the universe has an explanation of its existence, that explanation is God.
3. The universe exists.
4. The universe has an explanation for its existence.
2) It does not follow that if the universe has an explanation, that that explanation is God. Some versions of physics can posit multiverses, and some forms of quantum mechanics can almost make it so the universe exists because of itself. Or, to define God as such, basically tries to define away the argument, and doesn't actually answer the argument. Okay so, "God" exists, but what is it? How do you know it is such? And a variety of other questions. It's not an answer, it's a relocation of the problem.
And for number 1, if God exists, then what is his explanation for existing?
The Kalam Cosmological Argument:
1. Whatever begins to exist has a cause.
2. The universe began to exist.
3. Therefore, the universe has a cause.
Basically, the same as the above.
The Design Argument:
1. The fine-tuning of the universe is due to either physical necessity, chance, or design.
2. It is not due to physical necessity or chance.
3. Therefore, it is due to design.
And how is it that you so readily claim that it is not due to physical necessity or chance, and isn't that the question we're debating?
Perhaps there's more than one "universe," as we call them, and that in many others, the conditions aren't right for life, etc, and there's basically nothing. However, thermodynamics dictates the formation of most of the fundamental building blocks for life, and combine that with a very large universe, and lots of possibilities, and the very unlikely becomes true.
The Moral Argument:
1. If God does not exist, objective moral values and duties do not exist.
2. Objective moral values and duties do exist.
3. Therefore, God exists.
Number 1 works upon a fallaciously denying the antecedent (I believe I got the name right). Excuse my shorthand, but I'm feeling lazy: If God exists, then objective moral values exist. A -> B. God does not exist, then objective moral values and duties do not exist. ~A -> ~B. If it rains, and my car is outside, my car will be wet. It has not rained, therefor, my car will not be wet. As you can see, this is clearly false, because my car could be wet for other reasons.
Number 2 basically takes for granted something which doesn't appear to be true. There's
some general consensus surrounding human morality, but there definitely isn't anything near enough similarity to say objective moral value exists. On top of that, this only takes into account
human morality, and unwarrantly ignores how other animals and living things behave, act, and what kind of morality they follow.
The premises are rather dubious, if you ask me. Under the best case scenario, "God" becomes a term so broad and begging of questions, that it sorta defeats the point of what we set out to do in the first place. It becomes an empty answer.