What is the Purpose of the Mishkan?
The Torah writes (Exodus 25:8):As a Place for the ShechinaAnd let them make Me a sanctuary that I may dwell among them
Bechor Shor (ibid 25:2) writes:
... And G-d commanded him [Moses] to prepare that they should make a Tabernacle and the House of Holy of Holies, and in it an Ark, and in the Ark the Tablets, and there the Shechina will dwell with the Torah and the Jewish people will surround it like the Throne of Glory with the Shechina among them, like it says "that I may well among them" like among the angels...
And the secret of the tabernacle is that the glory of God that dwelt on Mount Sinai, [also] hiddenly dwells upon it. And it is like it is written there (Exodus 24:16), "And the glory of the Lord dwells upon Mount Sinai," and it is written (Deuteronomy 5:21), "Behold, the Lord, our God, has shown us His glory and His greatness." And so [too] was it written about the tabernacle, "and the glory of the Lord, filled the tabernacle" (Exodus 40: 34)." And with the tabernacle, it twice mentioned, "and the glory of the Lord, filled the tabernacle" - corresponding to "His glory and His greatness." And the glory that was shown to them on Mount Sinai was always with Israel in the tabernacle.
Shadal (ibid 25:1) writes:
After they accepted all of the judgements and the Torahs and G-d became a King in Jeshurun, it is fitting that they should make a Temple to Him, like Kings so He can dwell among them and this will strenthen the unity of the nation and its intense attachment to the Torah ...
Sifrei Devarim (1) writes:
Rabbi Benaya says: when the Jews served an idol they deserved destruction, comes the gold of the Tabernacle and atones for the gold of the [Golden] Calf
Rabbeinu Bachya (25:6) writes:
In order to show that the sin had been completely forgiven, the Torah commences the list of contributions to be donated for building the Tabernacle with gold. This means that the very means which had caused their disgrace would now become the means by which G’d would express His goodwill. A Biblical verse expressing the same sentiment is found in Hoseah 7,3, ברעתם ישמחו מלך, ”with their very malice they make a king merry.”
The Sforno writes (Exodus 31:18):
after the Torah described all the spiritual accomplishments which should have resulted from the many days Moses had spent on the mountain with G’d, the Torah now has to explain why all these spiritual accomplishments G’d had envisaged did not in fact materialise so that it became necessary to build a Tabernacle, etc., in order to achieve these spiritual accomplishments via a different route. The Torah explains that the cause of this detour in the spiritual ascent of the people was the abuse they had made of the freedom of choice. They, who had been about to receive the set of Tablets made and written by G’d Himself at the end of Moses’ stay on Mount Sinai for forty days, who were all to personify the ideal of being priests, and a holy nation, rebelled, corrupted themselves, as testified in Exodus 33,6 when they divested themselves of the signs of the covenant G’d had made with them, removing the garments emblazoned with the blood of that covenant.(see also another explanation in the name of Rabbi Y. B. Soloveitchik as related to Adam)
The Rambam writes (Moreh 3:32):
The Ramban argues (Vayikra 1:9):... It is, namely, impossible to go suddenly from one extreme to the other: ... Now God sent Moses to make [the Israelites] a kingdom of priests and a holy nation (Exod. 19:6) by means of the knowledge of God ... But the custom which was in those days general among all men, and the general mode of worship in which the Israelites were brought up, consisted in sacrificing animals in those temples which contained certain images, to bow down to those images, and to burn incense before them; religious and ascetic persons were in those days the persons that were devoted to the service in the temples erected to the stars, as has been explained by us. It was in accordance with the wisdom and plan of God, as displayed in the whole Creation, that He did not command us to give up and to discontinue all these manners of service; for to obey such a commandment it would have been contrary to the nature of man, who generally cleaves to that to which he is used; it would in those days have made the same impression as a prophet would make at present if he called us to the service of God and told us in His name, that we should not pray to Him, not fast, not seek His help in time of trouble; that we should serve Him in thought, and not by any action. For this reason God allowed these kinds of service to continue; He transferred to His service that which had formerly served as a worship of created beings, and of things imaginary and unreal, and commanded us to serve Him in the same manner; ... He made it obligatory that certain gifts, called the gifts of the Levites and the priests, should be assigned to them for their maintenance while they are engaged in the service of the temple and its sacrifices. By this Divine plan it was effected that the traces of idolatry were blotted out, and the truly great principle of our faith, the Existence and Unity of God, was firmly established; this result was thus obtained without deterring or confusing the minds of the people by the abolition of the service to which they were accustomed and which alone was familiar to them. ...
Since the deeds of people are determined by thought, speech and action, God, may He be blessed, commanded that when he sins, he brings a sacrifice and place his hands upon him corresponding to the deed, and confess with his mouth corresponding to the speech, and burn the innards and the kidneys, as they are the instruments of thought and desire. And the limbs [of the sacrifice] correspond to the hands and feet of a person that does all of his work. And he sprinkles the blood on the altar corresponding to the blood of his soul, so that a person think in doing all of this that he sinned to God with his body and his soul, and it is fit for him that his blood be spilled and his body burnt; were it not for the kindness of the Creator, who took an exchange and ransom from him [in] the sacrifice - that its blood be instead of his blood and its soul be instead of his soul. And the central limbs correspond to his central limbs. And the portions with which to sustain the teachers of Torah [are so] that they will pray for him. And the daily sacrifice is because there is no saving the community from always sinning. And these words are tenable [and] grab the heart, like the words of classic homiletic teachings (Shabbat 87a). And in the way of truth (mysticism), the sacrifices contain a hidden secret...