When you say God created life on earth what do you mean? Did he create one universal common ancestor or a number of living organisms/creatures? When you say guided things along was this through evolution or supernaturally?
Yes, I believe God created one universal ancestor. The rest of history is His reproducing and refining life to suit Himself. To His guiding things along, I don't normally use the term "supernatural" because I don't believe in the supernatural. If something exists, it is natural. But I understand what you mean.
If we look to all the natural phenomena surrounding us we can reach several conclusions. Two conclusions I have reached are that life could not have spontaneously generated itself, and that modern life forms could not have evolved on their own, simply because there hasn't been enough time. But I'm sure people will disagree with that.
If we consider life as generating itself, we have to ask "how many times did it happen"? If some organism sprang forth from inorganic matter, that first organism would have had no capability to reproduce and would quite quickly have gone extinct. The process would then have had to repeat itself countless times over countless time. So how long did that take?
If we look at modern man, modern people generally have two eyes. Modern fish generally have two eyes. It's not hard to deduce that there was some common ancestor of both men and fish that developed at some time not only one, but two eyes. How long ago was that, and what was the time frame between the development of two eyes and that original organism? There wasn't enough time.
Aside from the problem of time, we have the problem of death. Why do things die? What is the evolutionary need for death if not so that new life forms can take the place of older life forms. When you see a pattern like that developing it implies an intelligence behind it.