But the fact is, everyone does theology. Everyone has a belief system that informs, directs, and moves their life. Everyone has a worldview, a lens through which life and circumstances are interpreted and acted upon. Everyone has a religion, even a religion of unbelief and skepticism. In short, all of us who are sentient are theologians. We all make statements of faith, and each of us has some understand of the Divine. All that comes from the imago Dei in each person.
What is theology? Simply it is the study of God. What is "doing theology?" It is the doing of the study of God, which is something you don't have to go to seminary to do. Why is there a misconception? Because somewhere along the way the Academy was where theology was done and the Church was for regular folks. But theology is important not just for the Academy, but for the Church, because it is through theology done well and done faithfully that a believer comes to a fuller and more complete understanding of God, Christ, Holy Spirit, the Scripture, the Church, salvation, sin, mankind, etc.
Here are some reasons I have used before for why I believe every Christian should desire theology:
1) It is a non-exhaustive subject - You will never fully understand everything about it, so the quest is as fresh for the 50 year veteran as it is for the spiritual infant. The limits are infinite, so the depth and range of study is immense. My roommate in Seminary once shared the illustration that the Bible is a huge river that a child can drink from and play in the shallows and also where the most experienced diver can go as deep and as far and never reach the bottom.
2) Theology informs - Truth is gathered not through subjective experience, but through objective statements. You cannot "feel" Truth, you can only "know" it. Therefore, study leads to a deeper understanding of the truths of Scripture. If your belief cannot be backed with Scripture, then it needs to disappear. If Scripture challenges a previously held belief, then you need to pour and labor to determine if your view needs editing or deleting. Our doctrine should not be based on feeling, bias, or predisposition, but should instead be rooted in Scripture.
3) Theology loves - Anyone who spends any amount of time digging into Truth and doesn't come away with a deeper level of the double-love of God and Neighbor is a fool who wasted his time. I can't be any more blunt than that. Truly understand doctrine should not lead one to a dead intellectual understanding, but should drive the student of Scripture to a deeper relationship with God through Christ, and a more burning desire to love and minister to other people. Good theology is what makes a person memorize whole books of the Bible, travel to a soup kitchen down the road and a village in West Africa to share the message of hope, teach his/her children to love God and the Bible from an early age, drop notes of encouragement to a co-worker going through family and financial hardship, and the list goes on. Theology loves, theology bleeds, theology dies.
4) Theology shapes - Many times we see in Scripture the words conform and transform, referring to us as believers as we are progressively sanctified to be more like Christ. What do I mean by theology shapes? Simply, that as we grow in our knowledge of God we ought to become more and more like Christ. A deeper understand of the holiness of God and the triumphal power of the Spirit should aid a believer in the war against sin. Shaping implies that we have a proper understanding of our fallen condition and that we cannot do the shaping on our own, it is dependent on the power of God.
5) Theology prevents - Good theology prevents bad theology from taking over one's life and drawing someone away from the fold. Many cult-like sects of pseudo-Christianity are thriving because they find a population base that doesn't know enough about the Bible to know when they're being deceived (i.e. Mormonism and Jehovah's Witnesses). Good theology stops someone from traveling down a road of peril because they are more apt to see the signs on the road and where they will eventually lead. Good theology also prevents things like pragmatism, relativism, and entertainment from creeping into the church (IMO three of the biggest problems in the American church today). Good theology enables a believer to work to prevent someone else from falling to destruction or to believe in sin without consequence.
6) Theology is accessible - You don't have to spend a fortune anymore to get good resources. Many times all you need is a Google search and you can look up any issue you desire. Through the Internet and the digitalization of media, books are readily accessible. Very few in the Church can have the excuse that they don't pursue because they can't. You also cannot use the time issue. Typically, the people I find who don't have the time to pursue something are the ones who spend all their time updating their Facebook or playing video games. If something is a true desire, you will make time for it.
7) Theology is good - There are very few things in the world that can surpass the study of the God of the Universe. I may be biased there, but very limit can match up to the overwhelming joy and satisfaction that comes from hours of study about who God is. Theology is not something to fear, nor is it something to leave to the Seminary or to the Academy. Leaving it to the Seminary is what got Southern in so much trouble with liberalism and utter insanity from the 40's to 1993. Theology is first and foremost for the Church, because that is who Jesus died for and the Church is the people of God who are this radically different community. Theology is for them, to be applied to daily life, not something to be held at a distance as a scary object.
I am not saying everyone needs to go to Seminary. Trust me, not everyone does. Not everyone has been called, and not everyone is cut out for it. But that should not preclude anyone from thinking they can't or shouldn't be a student of theology. Sit under the discipleship and mentoring of a pastor or elder saint, read good authors and good books (there's enough mindless garbage out there, why not strengthen brain cells instead of killing them), but more importantly than anything else wear out your knees reading Scripture in prayer. Pour over the whole counsel of God's Word, and seek out good commentaries and sources to aid you.
Here are some books that may be of some help to get you started:
J.I. Packer Concise Theology, Knowing God
ESV Study Bible
Wayne Grudem Christian Beliefs
Paul Little Know What You Believe
Grahame Goldsworthy According to Plan
A couple good references
Wayne Grudem Systematic Theology
Danny Akin Theology for the Church
John Frame The Doctrine of God
Holman Series - From LifeWay
John MacArthur's New Testament
New American Commentary
Kistemaker and Hendriksen's New Testament Commentary
Matthew Henry - All the Bible in one volume, nice desk reference