Love how you closed this and how it points to learning the stories of people who have transitioned from religious true belief to unbelief as essential. The transition is a slow march to a tipping point that only seems sudden. Julia Sweeney's Letting Go of God is a perfect case. The "out of nowhere" realization that there was no god that happened in her backyard was the product of years of processing. It's better to talk to people as if they're on a long road instead of just insisting they're lost.
This reminds me a lot of Carl Sagan's comment about how open-mindedness and skepticism "are in some tension" but if you give in to either one wholly you are lost.
The idea of the internet silo or the echo chamber is tempting, but there's evidence it's exaggerated. http://www.slate.com/articles/technology/technology/2012/01/online_echo_chambers_a_study_of_250_million_facebook_users_reveals_the_web_isn_t_as_polarized_as_we_thought_.html