With all due respect, your opening sentence is flawed in regards to definitions. Most people assume that you must either believe evolution OR God created everything. However, the vast majority of evolutionary research deals with the development of the organic and non-living world based on evidence from all over the world. Evolution doesn't need to have an answer for the beginning for it to be true. Here are a few observations:
(1) No one has yet to prove through empirical evidence just how everything came into existence. The Creationist (whether Christian or other) believes that a god (again depending on the religion) created all that exists from nothing. This of course cannot be proved in any concrete way. It's believed by faith based on either written or oral traditions. On the other hand, evolution has produced several theories about how the universe could have come into being through naturalistic means, but these theories are also unproven thus far. Most people agree that indeed a "Big Bang" was responsible for the beginning---who or what is responsible for the BB is the debatable point.
(2) Evolution is an established scientific system. It has been and is being observed today by scientists all over the world. As stated above, evolution makes sense of the evidence that IS available to us today, and that evidence overwhelmingly supports evolution. Almost the entire scientific community world-wide is agreed that evolution is the most probable and reasonable explanation for the development of the world and universe. Therefore, whether a god created everything or the universe arose through natural means, it is not necessary to be in conflict with evolution.
Here are some helpful definitions dealing with science: http://www.nas.edu/evolution/Definitions.html
This page will help reinforce the fact of evolution: