I have a coworker, that is an "elder" at his kingdom hall, (at 28 yrs old) and we are to have a theological debate at some point this summer, which I am praying will lead to his salvation.

As far as manners, and work ethics, he's spotless, but he downloads just as many movies as anyone else, and brews his own beer for a big inventory.

My question is, how do I start a discussion with him, and besides being Christ focused (Trinity, Atonement for our sins, Deity and so on), I have never had deep discussions with this cult, and would like to be somewhat prepared.

Is there any one here that has had some exposure/experience with them, and where to challenge them without being offensive/rude but at the same time, being firm on doctrine.