There are few more hurtful sounds than hearing a loved one being slandered.  Blasphemy is slander against God, and it ought to be highly offensive to those who love Jesus.   Peter is describing the characteristics of false teachers who were infiltrating the church.  As we saw in the previous verses (2 Peter 2:10-11), arrogance and slander walk darkly together.  In this verse, we see that blasphemy and ignorance are linked.  Anybody who has a full understanding of the awesomeness of Almighty God, with His limitless power to strengthen the church and destroy the wicked, would surely never dare to offend His honour.  But blasphemy will thrive where there is ignorance of God, His character, His Word and His works.
 
Peter declares that the false teachers of the early church were not only puffed up with their own importance, but they did not know what they were talking about.  They were responding to their unknown inner passions.  Just like wild animals, they were doing whatever would satisfy themselves; and they had no concept of the consequence of their actions or personal lusts.  Although it seems a rather harsh analysis, they behaved towards God like animals with no souls, and were setting themselves up to forfeit their souls (Matthew 16:24-27).

The Apostle Paul admitted in 1 Timothy 1:13 that had been his experience, “Even though I was once a blasphemer and a persecutor and a violent man, I was shown mercy because I acted in ignorance and unbelief.”  This gives hope that when ignorant blasphemers turn to God in repentance and faith, they can be forgiven and accepted.  However, today's verse is a potent reminder of the hazards of assuming to be a teacher when you don't know what you are talking about (James 3:1). Those who presume to speak in Christ's Name but without His authority are treading dangerously.

So too are our friends and colleagues who blaspheme in ignorance, using Divine Names as verbal playthings (Exodus 20:7).  However, what is needed is not just a change of behaviour, but a change of heart.  Such transformation is impossible without being informed of the truth; and that is why we must proclaim the gospel (Romans 10:14).  Mouths that offend God will only start to please Him when they hear and accept what He says about Himself in the Scriptures.  Then their ignorance will be removed, and we might pray that they will believe what they hear. Then their animal nature will be replaced by a heart which is sensitive to please God.