Going to Church or belonging to an organization does not make one a Christian.
AMEN!!!!
I would add not belonging to a church does not mean one is not a Christian.
Yes but it helps, a lot. It's easy enough to talk yourself into falsehoods even with a solid theology to serve as a framework around which to build your thoughts. Just recently talked with clergy to make sure my thinking hadn't gone astray; hadn't missed something or fallen into one of the many philosophical pitfalls.
What makes you think his thinking hasn't gone astray?
The Christian mystic like the Zen Buddhist doesn't rely on others to tell him what to think. The Church Christian on the other hand, like the Buddhist does rely on others to tell him what to think.