Good without God. This is the motto for some Atheist groups and has been put up on billboards and buses.
I chose this to start with because it is probably the best way to say how I feel about being an Atheist. I have good morals and ethics as do my children. I worked with a young woman for awhile who had been taught by her parents and her church that Atheists were horrible, immoral people. She was very surprised to learn that I was an Atheist. "But Doris, your so normal and your children are so nice and well brought up!" We had some interesting discussions while she worked with me. I don't think I convinced her to be a non-believer anymore than she convinced me to believe but I think I did have her questioning some of the things she was taught about us heathen people!
I believe that morals and ethics are a direct result of tribe behavior. They are a societal outcome. The morals of a society are a direct result of the reactions of the whole to the actions of the one. Good morals and good ethical treatment (do unto others as you would have them do unto you) were around long before the christian religion. Much of what we consider "God's teachings" of what is moral and ethical were already being practiced by people who had never heard about Judaism or Christianity.
Good morals abound in those that belong to non christian religions as well as those that have no religion at all. I choose to have good morals and ethics as the way to live my life as a good person and respect for my fellow humans, not because some being threatens me to do so. I live my life as a good person, not because there is an ethereal eternal life awaiting me or eternal damnation if I don't, but because that is how I wish my children to live. I prefer to be a good example for good's sake and not because of an imaginary punishment after death.
I am an Atheist because there is no proof of a God, any God. Yes, there are many things yet to be explained, but that is the wonder of the world. Constant questions and discoveries. Science forges on questioning and finding the answers. Religion, well, religion just keeps denying. Reminds me of the workers who keep doing something the hard way because that's "the way it's always been done" even though there are much smarter and easier ways to do it.