I agree that only God can speak for God and I appreciate the way you address that. It is painful to see or hear of someone turning their back on God, not because of who He is, but because of sinful, flawed human beings who represent Him. 

I like the sound of the amputation line but I believe He is a God that amputates. I believe He wants to amputate the things that are displeasing to Him and harmful to us. He also prunes us so that we can continue to grow and thrive spiritually and develop into the person He has called us to be. God desires the vey best for our lives . . .
John 15 says 
Jesus Is the Vine--Followers Are Branches
1" I am the true vine, and My Father is the vinedresser.
2"Every branch in Me that does not bear fruit, He takes away; and every branch that bears fruit, He prunes it so that it may bear more fruit.