I don't even know what to say that hasn't already been said by those with louder voices, and better turns of phrase.
But I feel as someone who has been a part of the Atheist/New Atheist movement for as long as I have must stand up and say "I reject that man. I reject that murderer."
Yes, I apparently have some level of belief system in common with that man, but I will not let him represent me. I will stand with honest, honorable religious people, from any walk who are working to make this world a better place before I will ever stand with an Atheist who has so little respect for life as to murder.
My heart breaks for the families who lost their son and daughters. They are the ones who need to be remembered.
Deah Shaddy Barakat, Yusor Mohammad, Razan Mohammad Abu-Salha, you are gone now, and wrongfully so. My sincerest condolences to your families.