Lack of understanding doesn't prove a god exists

One of the arguments which comes up often begins 'If there's no god, how do you explain...?' 

Things that usually appear at the end are along the lines of 'creation', 'life', 'people' and 'everything'. 

I've never seen anything at the end of the '...how do you explain...?' question which even remotely suggests a god exists. The logical fallacy here is known as variously as The Argument From Ignorance (Latin: argumentum ad ignorantiam), the Appeal to Ignorance, or the Argument from Personal Incredulity. 

The issue lies with the theist arguing that a god must be true because he hasn't been proven false or that there isn't a natural explanation known so a god must be responsible. 

Life: When a person argues that god must be real because there's life, they are clearly ignorant of abiogenesis. The process by which life forms from non-living matter. Has it been shown beyond doubt that abiogenesis is responsible for life on Earth? Not to my knowledge. But what the research in the field shows is that it's possible, and I for one am confident that in the not too distant future we'll be hearing some major and exciting announcements in this area. 

People: Let's keep this simple. Evolution explains people. Man didn't appear suddenly from dust and a woman from his rib. People evolved. 'People' is put at the end of the 'how do you explain...? question when the person asking it doesn't understand evolution. That's all there is to it. 

(and keep in mind, abiogenesis is not necessary for evolution, evolution starts only once there is life)

Creation: When someone asks me, as an atheist, how do I explain creation I ask why they think this is a creation. To try to explain why creation exists and you've already conceded a point which hasn't yet been demonstrated - this is not necessarily a creation. I've been given no reason to think the universe was deliberately created. Don't let anyone start with this as an assumption, get them to demonstrate why this is a creation at all. 

Everything: I've written a blog here about how what we can see is not proof of god. It specifically addresses the "look around you" argument people make. Everything we see either has a natural explanation or no known explanation yet. The 'everything' question also fails to address the current work going on in the 'universe from nothing' field (such as the book by the same name by Lawrence Krauss). 

Bottom line is, when someone says 'If there's no god, how do you explain...?' there is something they don't understand. Either that knowledge exists and they're just not aware of it, or our investigations have not yet found the answers. Yet. That's important to remember - not knowing something now doesn't mean we'll never know. 

To argue that we can't create life or that we don't know what caused the universe to be in this state is to be like a person from the 1400s arguing that mankind can never make it to the moon. To argue that evolution is not responsible for the diversity of life is to argue that gravity is not the reason things fall when you drop them. 

One person's lack of knowledge is not proof a god exists.