I control the conversation by saying:
"I know you feel you need to ask those questions, but I have already answered to the people that need to know." Then change the subject.
I suppose if you like and/or respect this person this might seem abrupt; but ask yourself, would you let your friends talk to you this way?
If they believe they are really a Christian and worship God, they will know that Christ and God are the only ones you need to answer to.
Blondie