There are various materials used in the construction of the Mishkan. One of the most prominent ones is gold. This is a little strange, considering the fact that the golden calf was made of gold, and is considered to be one of the Jews' big time mess-ups (There are opinions who say that we are still suffering today because of that sin.). In any case, we have a few questions about gold that beg for explanation:
1) Why is so much of the Mishkan made of gold?
2) We have a principal that the Cohen Gadol cannot wear gold into the Holy of Holies on Yom Kippur, because gold is what the Jews sinned with in making the golden calf. The principal is called "Ein HaKateigor Naasis HaSaneigor" - "The prosecutor cannot become the defender," therefore gold cannot gain atonement for the Jews, since that is what they sinned with. So how is it that so much of the Bais HaMikdash is made of gold?! The Holy Ark, the Menorah, the Shulchan, the inner Altar, etc., were all made of gold! We know that the objects that the Cohen wore atoned for different transgressions. One of his garments was the Tzitz; a gold band he wore on his forehead! How does this work?
The Ritva asks a similar question on the Gemara Rosh HaShana (26a). He says that the Caf and Machteh (instruments used by the Cohen Gadol to do the service on Yom Kippur) are also gold, and are used on Yom Kippur! Why don't they fall under the category of "Ein Kateigor Naasis HaSaneigor?" Even if you say that these instruments were used outside of the Holy of Holies, and the problem of EKN"H only applies inside of the Holy of Holies - the Ark of the Covenant was made of gold!
He answers his own question by making the following distinction: These instruments, and the Ark are all vessels, and the Cohen doesn't (in fact he can't) get any physical benefit (Hana'ah) from them. His clothing though, he does get benefit from, and so he cannot wear anything made of gold on Yom Kippur.
The Meiri adds that the Caf and Machteh aren't beautiful objects that bring delight to the user, they are simply vessels to be used. A Shofar on the other hand, is an object that the listener gets delight from because of its pleasant sounds. That is why we cannot use the horn of a cow as a Shofar -- "Ein Kateigor Naasis HaSaneigor."
That is what the Talmud Bavli has to say. The Yerushalmi has a different reason altogether. It says in the Yerushalmi (Yuma 7:3) it says that the reason the Cohen Gadol cannot wear gold into the Holy of Holies is because of "Gaiva" - "Arrogance." The Bavli seems to make sense, one cannot atone for his sins while getting pleasure from that which he sinned with! But, according to the Yerushalmi, what does arrogance have to do with anything?
Obviously, there is some sort of connection between the Cohen Gadol going into the Holy of Holies on Yom Kippur and the Golden Calf. What is the relationship, and what does it have to do with arrogance?
The Ibn Ezra tells us that Bnei Yisrael wanted to replace Moshe, whom they left for dead with an intermediary. Bnei Yisrael figured that Moshe had died, since he did not return on the day that they calculated he should. They figured that since G-d spoke through Moshe and he was no longer around, they would need a new vessel through which they could communicate with G-d. The question is, why in the world did they pick a golden calf?
Rav Dessler explains that under Moshe, the Jews attained an incredible level of spirituality. All the miracles and demands of that spiritual existence, kept them strictly disciplined. Now that Moshe was no longer around, their commitment waned and they began to look for a more relaxed way of life. Instead of a difficult life of spirituality, they chose to turn to a more relaxed lifestyle; something they could be more comfortable with. What they wanted was a life more connected to natural acts, not supernatural ones. So they chose the image of an ox, which represents the elemental forces of nature. Their sin, according to Rav Dessler, was wanting a "customized religion." They wanted a religion that they could be comfortable with; something more relaxed, something easier, with less spiritual intensity. Relating directly to G-d was too much for them, they wanted this ox to be a "middle-man."
In this sense, gold too represents wealth, comfort, and the epitome of riches.
The Zohar points out that Bnei Yisrael ask for an "Elohim" of gold. Elokim, is of course the name of G-d which expresses His quality of being master of nature, maintaining that which already exists. (As opposed to Yud Key Vav Key, which expresses His quality of being the source of existence.)
The Ramban gives us a totally different approach to the ox and gold. He points out that they request an "Elohim" of gold, which often refers to human judges (Rashi says in Sanhedrin - Lashon S'rarah VeRabanus), and when Elokim is used as a name of G-d, it always implies strict divine justice (G'vurah). The Ramban goes on to say that the ox is the image on the left side of G-d's "chariot," and the left side in general represents this idea of restrained giving, or G'vurah (Most people are right-handed, which means that whenever they try to do something with their left hand, it will be "held-back" to a certain extent. We tie our Tefillin to our left arm, and tie our left shoelace first as expressions of this idea.). The Ramban says that this is why trouble always comes from the north -- because the Bais HaMikdash opened to the east, and from that perspective, north is on the left. That is why the ox was used in the golden calf according to him. Another dimension to this is that gold itself represents strict justice, because it appears as fire in Yechezkel's vision as Chazal say in Yuma (45a). The Ramban says that with Moshe gone, the people needed a leader. Aharon, who was the one who suggested the material and who was responsible for the outcome of the whole situation, did all he could to demonstrate to them who the "real" leader was (by trying to overwhelm them with symbols of divine justice and might).
The reason that the Bais HaMikdash was made of so much gold was to give it a pervading feeling of divine justice and might. The place where the sacrifices were brought, needed this atmosphere of divine justice.
What emerges from these two approaches are not only two explanations of the sin of the golden calf, but also two ways to view gold in general.
1) As representing divine justice, or
2) Corrupted by man to be used for his own power, comfort and wealth, independent of its source.
Perhaps the Ramban and Rav Dessler don't differ in their explanations. The Ramban is explaining the incident from the point of view of Aharon, and Rav Dessler from the perspective of Bnei Yisrael.
Of course much of the Bais HaMikdash is made of gold, but when man has the opportunity to get pleasure from it, we don't know how he will react. As the Ritva says, "We are only concerned that the sinner will not get pleasure from what he sinned with." On Yom Kippur we again have the situation when Bnei Yisrael is using the Cohen Gadol as an "intermediary," as it were, to receive atonement, and the paradox of gold -- which represents divine justice on the day of justice, when we sinned with exactly that! The two simply cannot go together.