In the beginning encourage him to miss meetings and service, plan things for weekends and spend time connecting with him. Be cautious because often those who appear weakest are most likely to run to the elders in a spiritual crisis to deflect attention from their own inadequacies. It is how witnesses are conditioned.
Asking questions is good don't try to push him to fast he will take time to process new thoughts and too much too soon may cause panic.
Good luck