You say that this is a question that comes up often. Perhaps from others? Or even from your own curious mind. Well than, let's answer this with logic that the mind can understand rather than quotes that your mind isn't accepting because it isn't piecing them together.
God created everything, including human beings. Because you were in fact created at one specific second, at a specific minute, of a specific day, than you know absolutely nothing that came before that second you were created. So, your mind has a conception of the world around you: "Everything has a beginning, like I have a beginning." And, that is a state of mind that every creature in this world has. Because they were created they have difficulty imagining a creature that doesn't have a "beginning".
In fact, we define our world by time, start, and finish, beginning, and end. But, understand that god, because he is the creator of everything, also created time. The very nature we have to begin, or to end, only exists because god created the concept. Before god created it, the concept of "beginning" never existed. The idea of a "beginning to everything" is something that only exists in your mind because you were created with a beginning! But, that doesn't mean that that is the truth of god, because before he created time beginnings and endings did not exist.
So then, you probably would, after taking that idea in, wonder to yourself "Than how does he exist if not within time?". Simply, he would have to exist in a place, and in a way, where time is not a factor. Someplace out of our "universe" in a way. Because, our universe HAS a beginning, he created it, therefor he cannot be living in it because he would have to be living in his own way before he created this universe.
Another possible question you might ask yourself is "Than, what is the 'present' time to god." And, to that I say, remember: he does not experience time like you do. Time is something he created for you. You experience past, present, future. He does not. He is outside of time as you know it because he created time. Now, realize, that doesn't mean that he can't see YOUR present. He can see what's happening everywhere, all the time, so he can happily look down upon you in your time-based life and see what you're doing in the present with a smile. But, just because he can look upon your present does not mean that he is limited to time the way that you know it, and feel it. He is something different from you, in a place different than where you live, and simply does not abide by the same rules that he has birthed you into. The rules for time, beginnings, and ends, is your gift. A special universe that he created for you.