To listen to Paul is to listen to the Lord Jesus Christ and God the Father.
To reverse the Gospel is to remove the Gospel - leaving only worthless rules.
Paul does not want the church to be anxious and fearful, he wants it to be humbly gripped by the Gospel.
Father in Heaven, thank You that You sent Jesus Christ to give Himself for my sins and deliver me from the present evil age. Thank You for this eternal gift of grace and peace to me and to all who have received the Gospel. Please grip me with the Gospel so I will live for Your glory. Please help me to grow in knowing, trusting and sharing Your one and only Gospel. In Jesus' Name, AMEN.