The individual who has impacted my life spiritually the most since I became a believer in 1997 in college is John Piper. Not because I know him personally, but because God used him through his preaching and teaching to mold my heart and to open my eyes to what it looks like to walk with the Lord.
When I first became a believer and started attending church, someone encouraged me to read Desiring God by Piper. This book changed me. Period.
He coined the phrase "God is more glorified in me when I am most satisfied in Him." I began to understand what it looked like not just to know about God, not even what it looked like to know Him personally... but I began to grasp what it looked like to desire Him. Piper's writings helped me understand not what it looked like to simply have Jesus as Lord of my life, but I began to understand what it looked like to desire Him as Lord of my life.
I have read almost every book he's written and listened to countless sermon's online. I am encouraged and challenged by his passion for Christ and his longing to ultimately be completely satisfied in Christ alone so that God would be most glorified. His writings just make sense to me. They connected the dots between what the bible was saying and how it all fit into our culture. And he was/is bold in going against the grain of culture. He truly demonstrated to me through his preaching and teaching what it looked like to fight the good fight of faith and to strive to bring Christ glory through dieing to self.
God used Him to change me and I'm thankful for His 33 years as a pastor of a church I never attended. I am kind of sad that I won't be listening to him preach anymore online and I'm not sure if he has intentions of writing more books... but I'm positive that God is not through with him yet and others will be impacted just as powerfully as I was during his new season of life.
If you have not had the opportunity to listen to his farewell sermon preached this past Sunday, you can do so here. He also posted on his minsitry website www.desiringGod.org First Day Thoughts On Not Being A Pastor.