By a member of the MuslimAnswers.net Team
بِسْمِ اللَّـهِ الرَّحْمَـٰنِ الرَّحِيم
I found an unusual question of a non-Muslim who asked, “Why does Existence exist?”. For the purposes of the question, he can accept that angels, humans, and even God exists, but he wanted to know why existence as such exists.
I have to say that as a Muslim, there are two types of existence: the existence of the creatures and the existence of Allah the Exalted. As far as the existence of the creatures is concerned, this existence is brought into actualization by Allah the Exalted, who at every moment brings entities and events into and out of existence (of course, the “moments” themselves are also created by Allah, as time is not an independently existing substratum – so we have to keep this in mind whenever we say that “Allah chose such a thing” or “Allah decided a certain thing”, etc.).
What we have then of the existence of creatures is the actualization of Allah’s Creative Action (Takwin) in choosing existence for them above non-existence (and whenever He chooses to annihilate them by choosing non-existence over existence for them).
But when it comes to Allah the Exalted, we have to remember that He is the Necessary Existent, whose Being is unlike that of the Creatures, since He is not under the restrictions of the created dimensions. Note that whether we consider Allah’s Existence as a “superadded” Attribute of Allah, or as an “attribute” that is basically His Being (i.e. Allah in His “Dhaat” or “Essence”), in both cases “Existence of Allah” is uncreated, and the vocabulary we use of the creatures cannot be applied to Allah. Once we understand this, it becomes clear that it is inapplicable to ask: “Why does Allah exist?”, since this is the fundamental and primary truth from which everything else derives.
Looking at the issue from a slightly different angle, when one asks “Why?” one is looking for a reason, a cause behind the event or being under consideration. But we know that Allah is Self-Sufficient and has no need for an “external cause” in order to justify His Existence.
Thus, it may be possible to discuss with someone who disbelieves in the Existence of Allah and show to him the rational proofs for His Existence, but once this is proven and the opponent accepts it as such, it is pointless for him to ask: “Why does the conclusive proof of Allah’s Existence prove that He Exists?” This is a tautological question, and we can only hope that our opponent understands it as such and accepts that the acceptance of proof of any premise does not require further proof.
From the above then, it is clear that we should treat Allah’s Existence as the ultimate fundamental basis of all truth, from which all other truths and postulates can be understood.
 On the link: http://www.sunniforum.com/forum/showthread.php?105583-Why-does-existence-exist, accessible as of the 29th of April 2013