Guard against heresy

"But I am afraid that, just as the snake with his cunning deduced Eve, your minds may be led astray from single-minded devotion to Christ." (2 Corinthians 11: 3)

St. Paul warns here that it is possible for one to change his mind about who Christ is and what he did. It is also possible for one to change his mind as to key content of the doctrine of our faith. How can one protect himself from these dangers? By prayer and assiduous devotion to the Sacraments particularly the Eucharist and the Penance, one develops a sense of the faith, "sensus fidei." This is an interior light that alerts us to false doctrine. The collective 'sensus fidei" of the faithful is a sure bulwark against heresy.

Moreover the third promise of Mary to those who say the Rosary is: "The Rosary shall be a powerful armor against hell; it will destroy vice, decrease sin, and defeat heresy."