Once you're born again you are no longer a descendant of Fallen Adam because you're now in Union with the second AdamJesus Christ through the new nature which is the very same nature that Jesus was born with in His Humanity. Mankind lost God's image at the fall very clearly denoted in Genesis 5:3. Atheists don't have God's image but have the image of Fallen Adam which is why they need to be born again and come in Union with the second Adam and His image which is God's image because the second Adam is in Union with God unlike the first Adam or Fallen Adam. Ever since the fall of Man every human being has been born of corruptible seed which is why we need to be born of Incorruptible seed which is part of the Regeneration of the human spirit (Titus3:5)