He jumped up, stood on his feet and began to walk - Acts 3:7-8
That is the power of a transformed life
This man was not looking for a miracle
The apostles had no money to give him but they did not leave him empty handed
Get up your mat and walk and he took off running and leaped and praise God
Thousands likely turned to Jesus Christ from the personal testimony of one man - Acts 4:4
A changed life is a powerful testimony to the reality of the gospel
You may not feel qualified to a large crowd about Bible doctrine or deep theology but can certainly testify to what God is doing in your life