Your question got me curious and I Googled "atheist business owners" and found one web site (www.4atheists.com) and a number of local meetups. Googling "atheist business success" brought up a lot of articles and one group, www.atheistnexus.org. If you have a creative side, you might like "The Atheists Way" and other books by Eric Maisel, Ph.D., an atheist creativity coach.
All this from your friendly HubPages Zen Buddhist Agnostic Spiritual Universal Christian - happy to help! :) (Joy and success to everyone, no matter what we believe!)