Brian,
I am very cautious as I write this. I no doubt step out on a limb...but I will give my opinion for what it is worth, and you, through the Holy Spirit and God's word, decide for yourself.
I'm not sure how to go about saying this...but I (and others I know) do see problems with Piper. Let me say also that I have read multiple books by Piper, have listened to sermons by him, have some dvd's by him, and have attended a church that he hepled plant. I am friends with pastor of said church, who attended the Bethlehem theological college and lived with Piper for two years. So I'm very familiar with his stuff.
The main thing is this:
[u]Piper equates the glory of the world to the glory of God.[/u]
This is part the message being preached:
"Have you ever witnessed a last second winning shot in basketball? It's glorious isn't it! And if you love that, you love God...because He is even more glorious!"
"Have you ever seen the Two Towers? When Gandalf comes over the hill to save the day, it's just amazing! Why, it's sends chills up your spine it's so glorious! And to think, all of that was created in some movie studio - imagine how glorious God is!" [He uses that example. Try the same argument but with the Matrix and you'll see how bad it is if you don't already.]
"The olympics are just astounding! The things those people can do - wow. When I see the olympics, I just think of how glorious God is."
John 2:15-16
Love not the world, neither the things that are in the world. If any man love the world, the love of the Father is not in him. For all that is in the world, the lust of the flesh, and the lust of the eyes, and the pride of life, is not of the Father, but is of the world.
By using examples like these and others, John Piper appeals directly to the pride of life that exists in all sinners. If I explain God to anyone as John Piper does in examples like these, there is no one on Earth who would reject God! [b]All sinner loves that thrilling last second shot and all sinner loves Gandalf who wields a sword and hacks down his enemies in battle - but no sinner loves Jesus who humbled Himself to the point of death, even death on cross, and commanded others to do the same.[/b] This is an irreconcialible fact.
Also, Piper has lower standards than I believe is right...others will disagree...but entertainment has no place in the life of Christian. Especialy not secular movies like Lord of the Rings or secular events like football and basketball games. I don't see how Christians can enjoy watching unbelievers pridefully compete with each other while getting paid millions of dollars to do so... Piper also approves of rap music, which I think is erroneous (which I say based on much research and on much firsthand experience).
Lastly, ask yourself this question: Why is John Piper so popular? My unrepentent family members like him. Teenagers I know living in sin like him. Churches who teach easy-believism like him. I liked him before I was saved. In fact, I have yet to meet someone who doesn't like John Piper. This does not automatically discredit him, but it does make me seriously question his teaching.
One more thing, not all of Piper's teaching is bad...but who has 100% bad teaching? Not even the Devil has 100% bad teaching (he quoted true scriptures to Jesus).
I have tried to explain my thoughts, but have likely done poorly...please ask questions if you're confused.
God give us wisdom,
Nile