One characteristic unifies this and the following passage (vv. 14 & 19): sowing discord. Previously, the father urged his pupil not to be lazy. Now he describes what a worthless person looks like. The contrast between the passage above and this one is quite stark (in the words of Charles Bridges): “What a contrast between the inactivity of the sluggard and the unwearied diligence of the naughty person!” (Bridges)
6:12 — A worthless person, a wicked man, goes about with crooked speech,
He is a worthless person (literally “man of Belial” in Hebrew, אָדָ֣ם בְּ֭לִיַּעַל) The word “denotes one who is implacably wicked and who agitates against all that is good.” (Waltke). His speech is crooked (or fraudulent speech) — one who “distorts the truth on which a straight and sound society is built” (Waltke).
6:13 — winks with his eyes, signals with his feet, points with his finger,
In summary, “With a hint here, and a wink or a gesture there, the troublemaker can sow discord at will—until God’s hour strikes for him.” (Kidner) The point is not we ought not to wink but these gestures should not be used to advance wickedness. Waltke and others note that these gestures may be expressions of superiority, condescending attitude, etc. “By his devious and invidious motions he attempts to derogate others and thereby to lower their status in the eyes of associates. In turn, a troublemaker feels superior, and this ego satisfaction is his ultimate desire and goal.” (Waltke, citing Pault).
6:14 — with perverted heart devises evil, continually sowing discord;
Similar to the way Paul describes the various facets of one’s body to teach the doctrine of total depravity, so the father describes how a worthless fellow oozes out wickedness. His speech eyes, feet, finger and now the heart are listed. The man of Belial devises evil in his heart; it is not just external behavior — it comes from the heart. “The heart is the core of a person from which emanate all actions, motives, and speech. The heart of an evil person is bent on evil.” (Longman)
The end result of these expressions of worthlessness and wickedness is that it sows discord. “All their choices (‘heart’) are malicious, because discord among the people, disruption of community consensus and family unity, are their aim. Such discord may even carry them into court to try to give legal expression of the contentiousness…” (suggested from the Hebrew word for discord – a judicial term). (Hubbard)
6:15 — therefore calamity will come upon him suddenly; in a moment he will be broken beyond healing.
Such a person will come to ruin; God will see to it. “They may seem as though they are getting away with their actions, but they will ultimately be ruined; that ruin will come suddenly and will not be reversible.” (Longman) “Sudden destruction is probably a sign of divine wrath and indirectly incorporates the troublemaker among the ranks of the wicked (see 3:25).” (Waltke)
ERGO — We are warned against living this kind of life. Being a sluggard is one thing; being a wicked troublemaker is another. Wickedness cannot live alone; it must spread and it will do what it can to express itself. What is interesting about this “worthless man” is that the ultimate expression of his iniquity is discord. That vice is once again highlighted in the next passage.
How does one sow discord in the church? Will it always appear to be malevolent and vindictive? This passage views sowing discord as the culmination of a wicked man. Why does the church and our culture not view this as a serious vice (or does it)?
 “…the climatic line of each is ‘sows discord’ (vv. 14, 19).” (Hubbard)
 Some have suggested that these gestures may be ancient expressions of sorcery (cf. McKane) or simply restless expressions of inner disquietude (cf. Longman).