John Wesley on 2 Thessalonians 2:7

He will surely be revealed; for the mystery - The deep, secret power of iniquity, just opposite to the power of godliness, already worketh. It began with the love of honour, and the desire of power; and is completed in the entire subversion of the gospel of Christ. This mystery of iniquity is not wholly confined to the Romish church, but extends itself to others also. It seems to consist of, Human inventions added to the written word. Mere outside performances put in the room of faith and love. Other mediators besides the man Christ Jesus. The two last branches, together with idolatry and bloodshed, are the direct consequences of the former; namely, the adding to the word of God. Already worketh - In the church. Only he that restraineth - That is, the potentate who successively has Rome in his power. The emperors, heathen or Christian; the kings, Goths or Lombards; the Carolingian or German emperors.