I'm about 6 months late with this post but here goes for anyone who stumbles across this blog and has read "The Shack"
In 1 Timothy 4:16 the apostle Paul admonishes Timothy
"Pay close attention to yourself and to your teaching; persevere in these things, for as you do this you will ensure salvation both for yourself and for those who hear you."
What is sad, is that many are angered with those of us who actually try and hold to sound doctrine. They will defend heretical books like the Shack because it is easier to become lazy in our study and lazy in defending the faith and allow ourselves to be swept away by every wind of doctrine.
As a result, we are no longer to be children, tossed here and there by waves and carried about by every wind of doctrine, by the trickery of men, by craftiness in deceitful scheming;
When we fail to watch our doctrine closely, we allow some heretic to come along and refer to God the father as a woman named "Papa". This should not be.
And please, spare me the "It's a work of fiction. Lighten up" line of rhetoric. This book has scratched the American Christian right where they itch. It tickles their ears and they eat it up. They say things like "Eat the meat, and spit out the bones". Folks...first of all, I don't see anything about meat and bones in Paul's letter to Timothy or anywhere else in Holy Scripture. Secondly, the "oneness" view of the trinity is not a "meat and bones" issue. We are talking about foundational understanding of who God is. The orthodox view of the Trinity has withstood attacks throughout the ages. The issue is settled and heretics like William P. Young will fall by the way like his Arian fathers before him in light of the glorious truths of God's mighty word.
If you call yourself Christian but have gotten caught up in the novelity of this book, please repent under the hand of the mighty God of Scripture.