In his 'Life of Sir Thomas Browne' (1756) Dr Samuel Johnson even suggests a motivation for the no-believers' zeal: "In proportion as they doubt the truth of their own doctrines, they are desirous to gain the attestation of another understanding; and industriously labour to win a proselyte, and eagerly catch at at the slightest pretence to dignify their sect with a celebrated name".
-Johnson at his rhetorical best! Don't you just love his use of the words "doctrines", "proselyte" and "sect", and does this not hoist the zealous atheist on his own petard ?