"Thus saith the LORD; Cursed be the man that trusteth in man, and maketh flesh his arm, and whose heart departeth from the LORD." (Jeremiah 17: 5)
"Cursed" in this verse renders the Hebrew word "arar", which also means "embitter". One major cause of bitterness stems from our insistence, whether we are saved in Christ or not, to depend on other people (including ourselves) to accomplish something in our lives, as if their power, as if their influence is greater than God's.
God's love to us commends that He has done everything for us:
"But God commendeth his love toward us, in that, while we were yet sinners, Christ died for us." (Romans 5: 8)
Later, Paul writes:
"What shall we then say to these things? If God be for us, who can be against us? 32He that spared not his own Son, but delivered him up for us all, how shall he not with him also freely give us all things? 33Who shall lay any thing to the charge of God's elect? It is God that justifieth. 34Who is he that condemneth? It is Christ that died, yea rather, that is risen again, who is even at the right hand of God, who also maketh intercession for us." (Romans 8: 31-34)
Returning back to Jeremiah 17: 5, the first mention of the word "man" renders the word "gibber", or "mighty man", which often refers to people who are righteous, who walk by faith in Christ.
The second reference to "man" in the same verse is actually "adam", or the human race, or also our flesh, ourselves, our own efforts.
So, even a righteous man, one who has believed on Jesus Christ for His salvation, can labor under a curse to the degree that he trusts in another man, or in his own efforts. to accomplish anything.
In effect, to the degree that we still look to ourselves to accomplish anything, we are then declaring by our actions that whatever problem we want to control is somehow greater than God, that He does not have the strength to see us through.
Can any such act of unbelief be any more arrogant?
When we recognize that we are saved not just from being bad, but from being dead in our trespasses, then we can appreciate the glorious goodness of God's grace in sending His Son not just to die for us, but to give us Himself: His life, His standing, His everything:
"19For the wisdom of this world is foolishness with God. For it is written, He taketh the wise in their own craftiness. 20And again, The Lord knoweth the thoughts of the wise, that they are vain. 21Therefore let no man glory in men. For all things are yours; 22Whether Paul, or Apollos, or Cephas, or the world, or life, or death, or things present, or things to come; all are yours; 23And ye are Christ's; and Christ is God's." (1 Corinthians 3: 19-23)