When I engage in debate online with Christians, I am frequently asked about the origins of everything.
This comes down to the question of, "Where did life come from?" or "Where did the universe come from?"
I am somewhat familiar with studies in astrophysics and evolutionary biology where the origns of life and the universe are studied. But those are not my fields of expertise, so I don't pretend to use a study for an answer. There is a better answer.
"I don't know"
That's an honest answer isn't it? It is also a scientific answer. It's an answer that invites inquiry, it's an answer that excites scientists.
"I don't know, but let's see if we can find out" is the start of most rational, scientific investigations. It is the beginning of a journey, and no one knows how long, or how far, this journey will take us.
Let's compare "I don't know" to the other common response, "God did it".
First, you must realize that "God did it" is assumed without evidence. There is no proof that "God did it", there is no way to know, for sure. So saying that "God did it" is inherently dishonest, because it is assuming a fact that you cannot know.
"God did it" shuts down inquiry. It stifles investigation and it discourages scientific exploration. It encourages us to be satisfied with the way things are now, it blocks us from attempting to imagine that things could be any better.
By saying that "God did it" the speaker is in fact saying that he or she isn't interested in learning anything further. The speaker is just fine with his or her present level of knowledge, and is comfortable in their ignorance. Saying that "God did it" is a cop-out.
Here is what we do know.
Science has, so far, never needed a supernatural explanation for any piece of acquired knowledge. Radios, Televisions, GPS systems, spaceships, immunizations, and photosynthesis all work just fine without needing the supernatural to function.
Everything that we currently know came about without the requirement of the supernatural. It is reasonable, in fact probable, to assume that everything we will eventually learn will be based upon natural, as opposed to supernatural, processes.
When someone tells you that "God did it", ask them - "How do you know?" When they ask you where everything came from say, "I don't know" - that's the honest truth.