In the beginning, G-d creates the entire universe, including time itself, out of nothingness. This process of creation continues for six days. On the seventh day, G-d rests, bringing into existence the spiritual universe of Shabbos, which returns to us every seven days. Adam and Chava - the Human pair - are placed in the Garden of Eden. Chava is enticed by the serpent to eat from the forbidden fruit of the "Tree of Knowledge of Good and Evil," and in turn gives the fruit to Adam. By absorbing "sin," Adam and Chava render themselves incapable of remaining in the spiritual paradise of Eden and are banished. Death and hard work (both physical and spiritual) now enter the world, together with pain in childbirth. Now begins the struggle to correct the sin of Adam and Chava, which will be the main subject of world history. Cain and Hevel, the first two children of Adam and Chava, bring offerings to G-d. Hevel gives the finest of his flock, and his offering is accepted, but Cain gives inferior produce and his offering is rejected. In the ensuing quarrel, Cain kills Hevel and is condemned to wander the earth. The Torah traces the genealogy of the other children of Adam and Chava, and the descendants of Cain until the birth of Noach. After the death of Sheis, Mankind descends into evil, and G-d decides that He will blot out man in a flood which will deluge the world. However, one man, Noach, finds favor with G-d.
“Let’s make man...” (1:26)
Our Sages teach, "Anyone haughty is like one who worships idols.” (Sotah 4)
Ostensibly it's difficult to see the connection between pride and idol worship, but with Rashi’s commentary in this week's Parsha we can offer an answer:
The Torah says, “Let’s make man...”
From this verse, it sounds as though G-d had help when He created man, which is an absurd idea. Rashi addresses the problem: “Although (the angels) did not assist G-d in man's creation, and there is room for the heretics to claim that the Torah itself indicates that many gods participated in the creation of man, the verse did not refrain for teaching us proper conduct — to act with the trait of humility. The greater should consult and take permission from the lesser.”
By his behavior, a haughty person implies that he doesn't believe that G-d used the word "We" to teach us this importance of humility, that the greater should ask the lesser. Therefore, a haughty person will understand the word na'aseh — "Let’s make,” — according to its more “obvious” meaning, that there exist multiple independent powers (G-d forbid!).
And the result of this trait of haughtiness is tantamount to idol worship.
Sources: Parshat Derachim in Mayana shel Torah