There are those who say that John Wesley was not a “systematic Theologian.” It is true, that although he wrote volumes and volumes on nearly every subject important to people at that time, he never published a systematic, comprehensive doctrinal statement. He did not write a dissertation laying out in an integrated systematic manner his theological thought. However, there is a grand coherence to Wesley's thinking if one understands the evolving core principles he followed.
    Wesley believed that the message of the Bible, from beginning to end, is the salvation of humankind through the love of God. That theme is constant and consistent.  He stated time after time in many different ways that salvation is “the entire work of God, from the dawning of grace in the soul until it is consummated in glory.”  Further he believed that salvation was “a present deliverance from sin, a restoration of the soul to its primitive health, its original purity; a recovery of the divine nature; the renewal of our souls after the image of God in righteousness and true holiness, in justice, mercy and truth.”
    Albert Outler writes that Wesley's understanding of the salvation process has an “axial theme” (a central point around which his understanding rotated):  “the recovery of the defaced image of God” in humankind. It is about as “systematic” as Wesley will be. A good example of this is the way he developed his theological beliefs about the image of God. John Wesley's understanding of the “image of God” is grounded in the Church of England's ninth Article of Religion: Original Sin. And that doctrine has its bases in Genesis and the early church teachers, most notably Augustine (354-430). 
    Genesis 1.27 says, “So God created humankind in his image, in the image of God he created them; male and female he created them.” Through rebellion against the created order, humankind lost this image of God and was judged to be completely corrupt.
    Augustine believed that humankind thus inherited a bent to sinning — a state given over to ignorance and insatiable desire. The human creature is helpless to overcome this condition by its own efforts.
    John Wesley, an evangelist, a tireless preacher, a courageous cleric. He probably should not be called a systematic theologian. He was not prone to meditation and philosophy in order to draft abstract truths. His way was to apply to real life those beliefs he felt in his heart and his head. In every way he was a practical theologian.