I have been a life long atheist and never been inclined to nihilism. I sure can defend my meaning of life, which is simply to enjoy every moment, to learn from every experience good and bad, to further not just myself but those of my family and if possible the society in which I live in. It benefits them all if we collectively share our knowledge and experiences. So that the future of my child and that of the people I know will hopefully be more enriched because of it. The meaning is up to you, if you wish to be nihilst then fine, but that would be your decision. Being an atheist just means not believing in any deities/gods/supernatural beings. It does not mean being a nihilst.The philosophies of one person does not necessarily mean it is the philosophy of everyone else that as a common belief.