Just have him show the scripture that says all who believe in the lord are saved then show the one where it says do not judge. You friend needs to protect himself from his kid. Change all his passwords locks on his doors etc.. They may want to Jc him just to see what's going on in his life and if he's ready to confess to some sins because everyone that leaves the Borg goes off and commits sins, didn't you know.
He should be prepare to deny everything and say that's here say where's you second witness?