Buddhism, overall, is complicated and simple at the same time.
There are many different Buddhist sects, although most adhere to the same moral and philosophical codes with slight differences between traditions.
Yes, there are some Buddhists who either believe that Buddha was God incarnate or that there is some undefined deity in control of the universe (not Zen Buddhists, which is a less pure form of Buddhism).
For clarification's sake, most Buddhists do not object to one believing in a god. That then begs the question: "Why don't Buddhists in general believe in on?" The answer to that question lies in the buddhist notion that origins are irrevelant to becoming enlightened. "Why focus on something that cannot be known in the present" would be the common response.
I don't believe that most Buddhists are atheists. They accept the mystery of life's origins without any certainty of a higher being or not. All believe, though, in a supreme energy, which is somewhat deitic in nature.
And last but not least, most Buddhists have a very deep love for the Catholic saints throughout history. In fact, most Buddhist religious believe that many of them reached "nirvana" on earth (Mother Theresa, St. Francis of Assisi, etc)