Bede : You therefore, brothers, being forewarned, be on guard, etc. Being forewarned, because foolish ones will introduce various errors, some denying the future judgment, some falsifying divine words, some interpreting wrongly, some loosening the restraints of luxury, others deceiving the hearts of the wretched with other fraudulent deceptions, be on guard, lest by any cunning of deceivers you might fall from the firmness of your faith. — Commentary on the Catholic Epistles Cyril of Alexandria : Peter has to warn his people so that they will not be deceived. Our Lord Jesus Christ himself warned us for our safety, that we should "beware of those who come to us in sheep's clothing, but inside they are ravenous wolves." And again: "Take care that you are not deceived. For many shall come in my name, saying, I am the Christ, and they will deceive many." And Paul cries: "Beware of dogs, beware of evil workers claiming to believe in the Lord Jesus." For those who deform the truth by their doctrines of ungodliness and works of evil are like those who killed the prophets and apostles. Indeed, they are worse, because they have killed not only the living but those who have been saved as well. — CATENA Oecumenius : Therefore, beloved, since you know this beforehand, take care that you are not led astray by the error of the wicked and fall from your own commitment, but grow in grace and knowledge of our Lord and Savior Jesus Christ. To Him be glory both now and to the day of eternity. Amen. Truly, he calls faith in the Lord its own commitment. And just as he concludes in his other Epistle with prayer, so in this one, he prays for an increase in faith in the Lord for them. — Commentary on 2 Peter