John Piper is a man devoted to God with a genuine desire to extol God’s glory. That is not in dispute. What is in dispute is Piper’s claim that his theodicy extol’s God glory. The following critique will seek to demonstrate that Piper’s theodicy is fundamentally at odds with scripture.
The core feature of Piper’s theology is found in the following quote:
“Everything that exists–including evil–is ordained by an infinitely holy and all-wise God to make the glory of Christ shine more brightly.” 
Piper additionally sums up the matter as follows: “He wills that evil come to pass that good may come of it.” 
Here Piper is following his sincere, yet misguided mentor, Jonathan Edwards, who likewise argued that God “willed to order things so that evil should come to pass, for the sake of the contrary good.” 
Let us pause at this juncture and take note of a critical distinction. The Bible is replete with accounts of God overruling the intentions of evil and even using the unintended, un-decreed evils of this fallen world to bring about a good. In this sense God exploits evil and is glorified as one who is capable of redeeming the evils done against us.
None of this is being contested. But Piper and Edwards go far beyond this and argue for a theological hermeneutic that asserts God divinely determined and rendered certain every sordid evil and perverse, God-dishonoring sin so that good and glory come.
However this is exactly what we cannot say. Why? Because scripture manifestly forbids it! The scriptures reject as slander any notion of moral virtue that would suggest such a theodicy.
For instance Paul argues: “But if by my lie God’s truth is amplified to His glory, why am I also still judged as a sinner? And why not say, just as some people slanderously claim we say, ‘Let us do what is evil so that good may come’? Their condemnation is deserved!” (Romans 3:7-8).
As is patently obvious, Paul condemns as reprehensible slander any notion of a person being morally justified or godly if such a person were to determine that evil happen so that good can come–even if such good is God’s glory being amplified in a context of evil.
Yet Piper would have us believe that the ultimate reason evil exists is directly correspondent with a theodicy that anchors God’s moral perfection into a determinative sovereignty that rendered certain every murder, rape, sexual depravity and God-dishonoring sin so that the good of his glory can be amplified and “shine more brightly.”
In such a muddled, theological framework God’s moral nature becomes indistinguishable from evil itself.
If all of this weren’t enough Paul additionally argues in Romans 6:9 that we “should not sin so that grace may abound.” But Piper’s unflinching commitment to his preconceived assumptions disregards all of this and would have us believe God determinatively rendered certain each person’s sins so that his grace and glory would abound.
The underlying mistake Piper makes is assuming God purposes evil for the purpose of good. Oddly enough Piper seems curiously unaware that Jesus already denounced such absurd theology as a “kingdom divided against itself not standing.”
Sincere as they are, both Edwards and Piper are masters at obscuring true meaning with words.  But let us not be taken in with such oratory. It is both theologically and morally bankrupt.
 In the sermon cited above Piper quotes Jonathan Edward’s answer to the question as to how God can be the ultimate cause and determiner of sin and yet not be its author. Notice how Edwards relies on the Arminian language of “permission” to extricate himself from the dilemma:
“If by ‘the author of sin,’ be meant the sinner, the agent, or the actor of sin, or the doer of a wicked thing… It would be a reproach and blasphemy, to suppose God to be the author of sin. In this sense, I utterly deny God to be the author of sin.” But, he argues, willing that sin exist in the world is not the same as sinning. God does not commit sin in willing that there be sin. God has established a world in which sin will indeed necessarily come to pass by God’s permission, but not by his “positive agency.”
Piper than goes on to quote Edwards further saying, “God is, Edwards says, the “permitter… of sin; and at the same time, a disposer of the states of events, in such a manner, for wise, holy and most excellent ends and purposes, that sin, if it be permitted… will most certainly and infallibly follow.” As is obvious Piper is being wholly inconsistent with the logic of his own position. In Calvinism all men sin necessarily in virtue of God irrevocably decreeing that they sin irresistibly. For in Calvinism it is impossible for men to choose against God’s decree. It is pointless to say God permits what he necessitates through an irresistible decree. Piper is intentionally obscuring the true horror of Calvinism by softening his language and borrowing Arminian terms to escape the logical implications of his own theology. Does God need to act as a middleman between his will determined and his will coming about? Does God need to get “permission” from himself to follow through with his own prior determinations? Such obvious doublespeak does not give Calvinists like Piper pause. He intentionally fudges to evade the logical implications placed upon his view. For Piper to say that God “permits” sin to come about through his infallible, determinative decree is to simply say God established a world whereby each sin happens of necessity–via God’s eternal decrees men are powerless to resist. In the Edwards/Piper/Calvinist scheme, man is powerless to control his nature. They redefine “freedom of will” as acting in accordance with one’s strongest motive, which is quite meaningless to say given the fact they also believe God determined which motives will indeed be the “strongest” and irresistibly move our wills in a predestined direction. All these implications are logically necessitated given their believe in an eternal, meticulously exhaustive decree of God. Adam’s sin, mankind’s consequent fallen nature, and every subsequent thought, motive, desire, and act are necessitated by God’s eternal, divine decree. A person can no more resist or act contrary to the eternal divine decree than he or she could create a universe. How then can we speak of God merely “permitting” these “necessitated” sinful acts?” See Ben Henshaw’s devastating critique of Piper’s sermon and reliance on Edwards ill-conceived theology at: http://arminianperspectives.wordpress.com/2012/03/13/john-piper-on-god-ordaining-all-sin-and-evil-part-1-an-arminian-response-to-pipers-first-question/ (June, 2012).