A key to being a Christian in more than name only, philosophy or culture, and not just affirming Christian doctrine and principles, is actual experience with God? I would call it factual and real, not just subjective and ‘feelings’ related, even if no one other than yourself is involved. I’ve pointed to some examples in my first post above, and one that I’ve repeated fairly often here is about one of Tim Keller’s parishioners:
Another is Phil Yancey. Nominal Christians and ‘mere professors’ can ‘deconvert’ and lose the faith they never really had.