I'm not sure of the exact thread, but this topic has sort of been discussed already. But i think when Henry said even God couldn't see the island, he was just using it as a figure of speech, not being literal.

As far as the ABC diary, i wouldn't trust it too much. Although its pretty likely what Mr. Ecko is building is a church, it hasn't been confirmed. The diary is just made up stuff (if i've heard correctly), not absolute fact.

lol, that being said, i too think its a church