Narcissistic personality mental disorder is a common disorder among militant atheists. Here are the symptoms.

Having an exaggerated sense of self-importance

Expecting to be recognized as superior even without achievements that warrant it

Exaggerating your achievements and talents

Being preoccupied with fantasies about success, power, brilliance, beauty or the perfect mate

Believing that you are superior and can only be understood by or associate with equally special people

Requiring constant admiration

Having a sense of entitlement

Expecting special favors and unquestioning compliance with your expectations

Taking advantage of others to get what you want

Having an inability or unwillingness to recognize the needs and feelings of others

Being envious of others and believing others envy you

Behaving in an arrogant or haughty manner

Although some features of narcissistic personality disorder may seem like having confidence, it’s not the same. Narcissistic personality disorder crosses the border of healthy confidence into thinking so highly of yourself that you put yourself on a pedestal and value yourself more than you value others.

Mayo Clinic