When God initiates our salvation, The Holy Spirit begins His indwelling work of regeneration of our hearts, sealing our guaranteed inheritance into God’s Kingdom. The mark of an earnest believer is the transformation, whether radical or gradual, of the person’s heart and mind which is evidenced by the fruit in our public and private lives — not that we are perfect and never sin once we are saved, but the work of The Holy Spirit’s sanctifying work in our lives is apparent and sin no longer dominates or defines our lives because Jesus Christ is the Lord of our life.
When we bear/present/display good fruit in our lives, it is because The Holy Spirit produces in us Love, Joy, Peace, Patience, Kindness, Goodness, Faithfulness, Meekness, and Self-Control. There will be a blog article that goes deeper into this, but suffice to say that without The Holy Spirit indwelling us, human beings are not capable of bearing good fruit.
We sin against God everyday. Scriptures tells us that we grieve The Holy Spirit, we quench Him (in other words, allowing sin to hinder His influence), we blaspheme Him, we insult Him, we lie to Him, and resist/neglect/rebel against Him (Ephesians 4:30, 1 Thessalonians 5:19, Mark 3:29, Hebrews 10:29, Acts 5:3-4. Acts 7:51). If this is convicting, it should be — The Holy Spirit does that too (John 16:8-11). Thank God Almighty that The Holy Spirit also EMPOWERS believers; granting strength to live in a manner that is not possible by our own human ability (see Acts 1:8, Ephesians 3:14-16, and 1 Thessalonians 1:5). The Spirit and the flesh are at war within us, but the power of the Holy Spirit subdues the flesh. As such, we must avail ourselves to His power as the weapon against sin (see Romans 8:6-9, Galatians 5:17-19) so that we would bear good fruit unto God’s glory.