Etymologically a person who is castus is one who refuses incastus; a person who is chaste is one who literally refuses incest.
Being chaste accepts distance, respects otherliness (which cannot be simply reduced to difference), and is psychologically, healthily self-differentiated.
Someone who is not chaste is etymologically incestuous. Incestuous people do not seek relationships but live in fusion and confusion. Fusion and confusion define incest. And if fusion and confusion are hallmarks of our time, then it would be neither inaccurate nor an overstatement to say that North American society is overtly incastus – incestuous – in its overall character and not simply in terms of its sexuality.
Mature sexuality is not prohibitive in nature…prohibition being only another reactive aspect of confusion.
Castus gives human relationships their sincerity and warmth and allows people to recognize one another with genuine respect.
Castus is the inner ability that allows anyone to affirm their own sexuality, recognize the personal and social nature of sexual impulses, and give them a meaningful place within human life as a whole.
Castus is well-ordered love that does not subordinate greater things to lesser ones.
– St. Augustine
You cannot be a baptized Christian and not be castus.