It was no less a Person than the Lord Jesus Himself who made the above warning/ proclamation!
We place all kinds of signs to alert people of one form of danger or the other, e.g., Beware of Dangerous Dogs, High Tension/Voltage, Tigers, Snakes, Crocodiles, Lions, moving Construction Vehicles, et cetera. Other signs loudly proclaim Ė Beware of fake/adulterated/expired drugs and products, et cetera.
But rarely do you ever find any sign anywhere warning us to beware of men. However, the Creator and Sustainer of all life forms alerted us by Himself to especially beware of the human race, (Matthew 10:17).
While He walked the earth, He Himself took heed to this caution, and that explains why He could never commit Himself to mankind, because according to the Scriptures, the Creator knew what was in man, (John 2:24-25).
Mankind is Godís crown of creation, yet it is the most potentially dangerous of all the created species. Man was created in the very image and similitude of God; however, Satan intruded at the very onset of creation to mar Godís most perfect handiwork Ė mankind. And that is why today, mankindís natural as well as default setting perilously tend towards deliberate mischief and mindless wickedness.
It seems that the more mankind moves towards so called civilization and modern advancement, the crueler and churlish we tend to become. Therefore, the only man who can trust entirely in himself is that man who is totally dead to all forms of sensation; but since this is rarely ever the case, the perverted heart of mankind must always be subject to progressive renewal by prolonged exposure to the transforming power of the Scriptures. Thus, Godís word is the only best known panacea that can cure the evils of the human heart.
In summing up, let the reader take heed and beware of men! Treachery runs and lurks in the blood of mankind. Treachery is mankindís default setting. No wonder that even the Creator Himself sadly proclaimed that manís heart is entirely evil, (Matthew 12:34-35; Luke 6:45), and that man loves wickedness with a passionate desperation, (Jeremiah 17:9). May the Lord help us!