As I said, a rather curious assertion for a professed atheist to make, unless we're into True Confessions® time here.
It can absent a priori leaps of faith about values. Most atheists who don't think there is a higher power make such leaps, and are thus not sociopaths, at least not in my experience. My totally atheist dad was about the most moral man I had the pleasure of knowing. I still miss his wisdom and guidance, and glowing "spirit." He had a gift.