If someone is determined not to accept, there is NOTHING you can do to change their mind.
If they are skeptical (which I think is better than cynical?), then all you can really do is keep chipping away.
If it helps, I wrote up my own story as a way of explaining my experiences to non-empaths. See http://empathcommunity.eliselebeau.com/profiles/blogs/we-are-all-connected-how-i-came-to-recognize-myself-as-an-empath
Good luck ... and best you can, be patient. With the rate consciousness is rising these days who know how quickly we might find ourselves as the new normal!