The preacher has been driven mad by something he saw in 'The Beacon', which is the centre of this worlds religious institution. His faith has been shaken; he believes that he's wasted his life for a lie and he seeks revenge. He should sound manic, especially his laugh. In the last line he should be feigning welcome, with the idea that he has malicious intentions for the girl who has just entered his room.

The general idea for the character is somewhat of a typical western preacher gone mad, and the voice to match. So a southern accent, but if you feel you can make something else work you'tr welcome to give it a shot.