Here as at other times Wesley let experience be his teacher. In his ministry he had found those persons who could testify to a salvation experience but who were still plagued by doubts and questions. He came to see this as one of the tools of Satan to rob the new believer of joy, peace, and power. Consequently, he preached the doctrine of assurance all the more, but now for motivation to grow rather than as a condition for salvation. We can understand this if we return to Wesley's understanding of Christianity as a relationship.
Authentic growth takes place when there is security and love in a relationship.
Wesley said this is what the Holy Spirit provides. He comes to our hearts to let us know that we are God's children. Dr. Ed Robb has said that if salvation is so insignificant that you can have it and not know it, then you can lose it and not tell it. It is the ministry of the Holy Spirit to bear witness to us that we are the children of God. Unfortunately, assurance has been misunderstood.