"The problematic theology in The Shack unfortunately detracts from some valuable aspects of its response to the problem of evil and suffering. One valuable element of the movie’s response to the problem is its hopeful message that there is no unredeemable suffering. God offers forgiveness even to the worst of sinners (so we should too!) and He is able to bring good out of even the most horrific evils. The movie also clearly communicates that although God allows suffering, which He then redeems, that does not mean that He is responsible for causing the suffering. As Papa explains to Mack, “I can work incredible good out of unspeakable tragedies. That doesn’t mean I orchestrate the tragedies.”"
End quote. Bold, my emphasis.
The problem is that a false god will always have a false definition of good and evil, sin and obedience. Therefore what "The Shack" offers in regard to evil and suffering will not be what the biblical God says and ONLY what the biblical God says is true and is useful for our sanctification and right thinking.
2Ti 3:15 and that from childhood you have known the sacred writings which are able to give you the wisdom that leads to salvation through faith which is in Christ Jesus.
2Ti 3:16 All Scripture is inspired by God and profitable for teaching, for reproof, for correction, for training in righteousness;
2Ti 3:17 so that the man of God may be adequate, equipped for every good work.
Those outside of Christ (like those who accept this false god of "The Shack") and are not of the elect indeed will have unredeemable pain and suffering. Suffering for sin isn't true suffering--it's justice.
For the believer ONLY, can we state most assuredly:
Rom 8:26 In the same way the Spirit also helps our weakness; for we do not know how to pray as we should, but the Spirit Himself intercedes for us with groanings too deep for words;
Rom 8:27 and He who searches the hearts knows what the mind of the Spirit is, because He intercedes for the saints according to the will of God.
Rom 8:28 And we know that God causes all things to work together for good to those who love God, to those who are called according to His purpose.
Rom 8:29 For those whom He foreknew, He also predestined to become conformed to the image of His Son, so that He would be the firstborn among many brethren;
Rom 8:30 and these whom He predestined, He also called; and these whom He called, He also justified; and these whom He justified, He also glorified.
Rom 8:31 What then shall we say to these things? If God is for us, who is against us?
And notice that "redeemable" suffering is entirely connected to the biblical Trinity. No biblical Trinity, means no salvation, which means no redeemable suffering. It's that simple.
Adam Pesler goes on to say:
"Another valuable element of the movie’s response to the problem of suffering is its poignant portrayal of a God who suffers with us. In The Shack the divine Persons never try to explain to Mack why his precious daughter was allowed to suffer and die, but they share in his deep sorrow, demonstrating their unfailing love for Mack and his daughter."
"To be clear, I do not encourage you to go see The Shack. The potentially healing aspects of the movie’s response to the problem of suffering are unfortunately bound up with unbiblical suggestions about the nature of God and the uniqueness of Christianity. Rather than spending your money on a movie ticket, I encourage you instead to buy a copy of Wolterstorff’s Lament for a Son or C. S. Lewis’s A Grief Observed and The Problem of Pain."
End quote. Italics, original. Bold, my emphasis.
God doesn't suffer. Not like humans do. To suggest that He does, is to suggest there is something mutable about Him, something lacking, something human. Now Scripture does say God is grieved by peoples' sin (particularly those by believers as Eph. 4 talks about). But that is not suffering. Man suffers loss for example, but the triune God does not. The biblical Jesus, who is God the Son, did suffered in His human flesh during His illegal trials and on the cross, but that was directly His alone and had everything to do with the atonement (He did also suffer infirmities as Hebrews states. He indeed was grieved but that wasn't an identifying with human grief. His sorrow was based on His standard and the violations made against Him and the perfect knowledge of just how totally depraved and dead in sin man is and what awaits those who are not chosen by Him for salvation. He never stopped being God ever, so even in His grief, He wasn't coming from a depraved, incomplete, without knowledge stance. To say God suffers when we do is really to make God man-centered which is blasphemy.
I believe that when God's people are persecuted, Scripture indicates that they are actually persecuting Him because 1) they belong to God and IN Christ, and are identified with Him and His name, and 2) we are the battleground on which the Devil is warring with God. I believe this is likely what Is. 63:9 is describing--also various other passages about the reproach of Christ which falls upon us). The world will hate us because we are in Christ and bear His fruit.
In regard to the false teachings of CS Lewis, go here.