“The LORD knoweth the thoughts of man, that they are vanity.” Psalm 94:11
Man’s thoughts are opposed to YHWH’s thoughts:
“For my thoughts are not your thoughts, neither are your ways my ways, saith the LORD.” Isaiah 55:8
In Psalm 94:11 man’s thoughts are called “vanity.” The Hebrew word translated with “vanity” in this text is hebel. And hebel is mostly used in the context of idols (vanities). Check a.o. Deuteronomy 32:21, 1 Kings 16:13, 26, Psalm 31:7, Jeremiah 2:5, 8:19 and 14:22 and Jonah 2:8.
If we worship idols, we are forsaking Him.
“They that observe lying vanities forsake their own mercy.” Jonah 2:8
So if Psalm 94:11 says man’s thoughts are idols (vanities, hebel), then we forsake Him if His thoughts are not our thoughts. If we do not serve Him with our thoughts, then we serve idols. If it is not His thoughts (Isaiah 55:8), then they are idolatrous (vanity) thoughts. If His thoughts are not in our heart, then there are idols in our heart.
“Now therefore put away, said he, the strange gods which are among you, and incline your heart unto the LORD God of Israel.” Joshua 24:23
“And Samuel said unto the people, Fear not: ye have done all this wickedness: yet turn not aside from following the LORD, but serve the LORD with all your heart; And turn ye not aside: for then should ye go after vain things, which cannot profit nor deliver; for they are vain.” 1 Samuel 12:20-21
Ecclesiastes is known for its frequent use of the word “hebel”.
“Vanity of vanities, saith the Preacher, vanity of vanities; all is vanity.”Eccl. 1:2
Our own works are vanity (idolatrous), if they are not His:
“I have seen all the works that are done under the sun; and, behold, all is vanity and vexation of spirit.” Eccl. 1:14
“Then I looked on all the works that my hands had wrought, and on the labour that I had laboured to do: and, behold, all was vanity and vexation of spirit, and there was no profit under the sun.” Eccl. 2:11
And desire is also vanity, according to Ecclesiastes.
“Better is the sight of the eyes than the wandering of the desire: this is also vanity and vexation of spirit.” Eccl. 6:9
Desire is in our heart.
“Ye have heard that it was said by them of old time, Thou shalt not commit adultery: But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart.” Matthew 5:27-28
“Thou shalt not covet …” Exodus 20:17
Idols are “vanity”. Idols are nothing.
“As concerning therefore the eating of those things that are offered in sacrifice unto idols, we know that an idol is nothing in the world, and that there is none other God but one.” 1 Corinthians 8:4
The thoughts of man are “nothing” for Him. And we must also hate them:
“I have hated them that regard lying vanities: but I trust in the LORD.” Psalm 31:6
Do you hate the thoughts of man in your heart and mind?