Here's m y response:
As I am not a Calvinist, I have no problem believing that this fellow was once a Christian.
Our noetic structures are like rafts. The beliefs that we hold are like the logs of the raft. We are constantly adding new logs to expand our raft, and getting rid of old logs are "leaky" or which don't fit together well with the new ones. What is interesting is the criteria we use to admit new logs and to eliminate old ones. I'll be curious to hear this fellow's story, and his criteria.