How to spot a false teacher

Today the Men's Tuesday morning group spent some time on 2nd Peter chapter 2. 
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Peter warns us that just like there were some false prophets in the old days (like Balam) there will be false teachers with us till the end. Peter not only tells us that false teachers are bad and dangerous, but he gives us a list of things to watch out for.  A checklist of characteristics of false teachers.  For instance, per 2Peter...

False Teachers...

• can work in secret from within the church (v1)
• deny the gospel (v1)
• are sensually attractive (v2, v18)
• cause others to blaspheme (v2, v14)
• are greedy and exploitative liars (v3, v14, v15)
• are irrational, follow their base instincts, and speak of things they don't know (v12)
• are bold, willful, open, public, and proud of sins of which they should be ashamed (v10, v13)
• they are adulterous, insatiable for sin (v14)
• they entice others to sin (v14)
• they falsely promise freedom (v19)

Peter gives us these characteristics so that we can be on the lookout for false teachers and he underscores this passage with an incredibly vivid proverb.