14 The inventor of all heresy was Simon Magus: that Simon, who in the Acts of the Apostles thought to purchase with money the unsaleable grace of the Spirit, and heard the words, You have neither part nor lot in this matter, and the rest: concerning whom also it is written, They went out from us, but they were not of us; for if they had been of us, they would have remained with us. This man, after he had been cast out by the Apostles, came to Rome, and gaining over one Helena a harlot, was the first that dared with blasphemous mouth to say that it was himself who appeared on Mount Sinai as the Father, and afterwards appeared among the Jews, not in real flesh but in seeming, as Christ Jesus, and afterwards as the Holy Spirit whom Christ promised to send as the Paraclete. And he so deceived the City of Rome that Claudius set up his statue, and wrote beneath it, in the language of the Romans, “Simoni Deo Sancto,” which being interpreted signifies, “To Simon the Holy God.”
Source: Catechetical Lectures (New Advent)