The Practicality of Doctrine

I recently read a book entitled The Five Views of Sanctification. It was a synopsis of several different doctrinal views of sanctification. I began the book realizing that I could barely define the term, much less give any detail of its ins and outs. As I began digging, all of this information I found became incredible practical. That led me to thinking about doctrine itself. I realized I had previously viewed doctrine as something better left to seminary students. I assumed (incorrectly) that it was difficult to grasp and would not really be worth my time. So how did this end up being practical? As a friend later pointed out, you often do what you think/believe. So the more I learn about doctrines of God, man in relation to God, the person and work of Christ, redemption etc., the better able I will be to know God in a deeper, more satisfying way than before. And as Piper has said, "God is most glorified in us when we are most satisfied in Him." And isn't that our "chief end. To glorify God and enjoy Him forever" (Westminster Catechism). So if we are going to glorify God by being satisfied in Him, and not the desires of the flesh (Gal. 5:24), and worshipping Him as is His due, then we must know more of ourselves and more of Him and more of what He has done in Christ to redeem His creation. And if we want/need to know more about these things, then we do so by studying His word and the doctrines it teaches us.
So if you have a sudden urge to run out and become a theologian, which as Christians we should be, then thankfully there are plenty of resources to direct us. A few of the ones I have found very helpful are:
   The Westminster Confession
   Systematic Theology by Louis Berkhof
   Calvin's Institutes of the Christian Religion
   Knowing God by J.I. Packer

Piper has a few other things to say on doctrine in his book God is the Gospel:
    "Doctrine means teaching, explaining, clarifying. Doctrine is part of the gospel because news can't be just  
    declared by the mouth of a herald-it has to be understood in the mind of a hearer...Gospel doctrine
    matters because the good news is so full and rich and wonderful that it must be opened like a treasure
    chest, and all its treasures brought out for the enjoyment of the world."