Talk about roller-coaster rides! B'nei Yisrael was riding so high, having heard at least two of the Ten Commandments from G-d Himself, the secrets of the Universe revealed right in front of their eyes. But then, they plummet downwards, hitting an all-time low with their worship of the Golden Calf. So enraged and shocked is Moshe that he drops the precious luchot from his hands. 
You cannot truly believe in HaShem, unless you also believe in yourself.


You cannot truly believe in HaShem, unless you also believe in yourself.

What happened, folks?
It's all about self-confidence and self-esteem; about conducting oneself in a dignified manner, because we are a dignified people. When Moshe did not come down from Mt. Sinai at the expected time, the Jews panicked.
"How are we going to engage with HaShem without an interlocutor, without our fearless leader Moses?" they cried out. And so, they devised their own "middle-man," the calf they had seen the Egyptians worship, and which they had used themselves as an offering to G-d.
They (we!) had revealed a major flaw in our spiritual make-up, a lesson we should never forget: you cannot truly believe in HaShem, unless you also believe in yourself. I must always remember that I am a unique, chosen creation of G-d, created consciously, specifically by the Almighty to carry out a holy mission in this world. The knowledge that I have meaning and purpose in this world energizes me to live up to my calling and serve G-d with humility, yet confidently.
Notice that the parsha begins with the unusual phrase, "Ki tisa et rosh B'nei Yisrael..." - "Lift up the heads of the people" - as a way of saying "count the people." Who counts in this world? One who holds his head up high.
This is also the lesson of our second reading this Shabbat, that of the Parah Aduma - the Red Heifer. Its ability to purify even the most tamei of individuals teaches us that no matter how far we've strayed, we are always capable of reaching an elevated stage and achieving closeness with HaShem.
At the same time, the fact that the Red Heifer renders its handler impure reminds us never to get carried away with our stature in life. The kohen who dispensed the b'racha of the Parah Aduma might have thought he was beyond sin, impervious to any defect; but this Bordeaux Bovine reminded him not to let his position go to his head.
We must strive for the right balance: we are human beings, frail and fallible; yet, we need never "cow"er in self-doubt.