Why is witnessing about what God has done important for Christians?

Witnessing about what God has done is essential for Christians as it reflects our faith and serves as a testimony to God's grace and power. In Mark 5, Jesus instructs the healed demoniac to share with his friends what the Lord has done for him. This directive emphasizes that our witness should focus on God's actions rather than our efforts. By recounting what God has accomplished in our lives—our salvation, His faithfulness, and His mercy—we proclaim the truth of the gospel and encourage others to recognize His sovereignty in their own lives.