I'm afraid I find your question rather confused. A "believer" is someone who believes in something religious. The belief may be belief about matters of fact (e.g. God exists and Mohammed was his prophet) or a trust placed in something (e.g. trusting in God). An ex-believer is someone who used to believe (in either sense) and no longer does; he either no longer thinks the factual statements are true or no longer is able or willing to place his trust as before.
An experience of having "met God" has no necessary connection to the matter of being a believer. One can believe without ever having such an experience, and one can have an intense experience and still not believe in its reality. Of course, some (many?) believers base their belief on having had such an experience, but lots don't. Of those who do, some will later decide that they misinterpreted an inner psychological experience as an encounter with an external personal being. That you want to deny such people their own understanding of their own experience is kind of obnoxious, but is unlikely to persuade anyone but yourself.