I think I'll like the book!
From this brief introduction, what I understand is that Gibson is saying go ahead and speak your heart and spirit and don't worry about being (culturally) "wrong," because culture will always regard "public (disclosure of) religion" to be wrong. And most of us know who's right in that regard.
I have a website and only this morning I included a gold cross image on it in comments section and found myself worrying if it would be upsetting and offputting to people...then I left it there because it's my site, and I like the image and I'm a Christian and it makes ME feel fine.
Loss of a certain popularity factor culturally is to be expected for, particularly, Christians. "In the world, but not of it..."
I have a huge amount of respect for Mr. Gibson. He took an incredible amount of slings, arrows and mud from groups of every stripe opposed to "The Passion of the Christ" and, at the end of the day, it became one of the greatest epic movies of recent time - all beacuse it was based on truth - and substantiated by the Bible.
What frightens me is that we are reverting to the mindless flocks of biblical times when tribalism dominated most cultures. Despite centuries of learning, progress and warfare, many of those old tribal alliances and ignorance are re-surfacing and beginning to dominate cultures across the earth. Perhaps we are witnessing the very beginnings of the 7 signs of the Apocalypse and Mr. Gibson knows far more than we can understand. Stranger things have happened.
What non-believers fear the most is Christ asking people to stand before a mirror to examine themselves.
Try telling someone, "I hope you get everything you deserve."
People don't like the ramifications of that statement knowing most of us have an immense fear of getting what we truly deserve.