A recent article by Arnon Segal in the Hebrew-language Makor Rishon reported on a news story that isn’t currently relevant but, God willing, will soon become vitally important. Segal asked Rabbi Yisrael Ariel, the founder of the Temple Institute, whether the Third Temple will descend from heaven or whether it requires that mankind will construct the prophesied dwelling place of the shechina (holy presence). Rabbi Ariel insists that Jewish sources teach that the Jews are commanded to build God’s house. He goes on to say that the concept of the Third Temple descending from heaven comes from Christianity and, more specifically, from the New Testament Book of John.
Segal opens by acknowledging that most sources (Oral law, Rambam, early and later sages, etc.) rule that the Third Temple will not simply descend fully formed from heaven. Indeed, this seems implicit in the Biblical mandate, “And let them make me a sanctuary that I may dwell among them” (Exodus 25:8).
The Rambam (Maimonides) lists the construction of the Temple as a positive commandment. This was clearly true for the Tabernacle as well as the two Temples that stood in Jerusalem which were all the products of earthly labor. The Rambam goes on to explain that the very fact that the Temple is being rebuilt will be a major sign that humanity has reached the End of Days.
Nonetheless, Midrash Tanchuma (Ki Tisa 13) teaches, “God said that in this world, you will build me a dwelling in the Temple surrounded by walls, but in the world to come, I will build you a sanctuary with walls of fire”, which is also brought in the Zohar. This also seems to be the position of Rashi (Sukkah 41a).

Indeed, it is written in the tractate Rosh Hashanah 30a, which deals with the counting of the Omer, the night before Passover. The question is posed: If the Temple were to be built on the night of the 14th to the 15th of Nissan, should we still count the Omer?
Rashi suggests the hypothesis that the Temple could be built in one night, hence the widespread idea that it will descend from above. How is it possible to construct such a large Temple in one night?
Segal suggests that many cite these sources in order to exempt themselves from the responsibility of building the house of God. He turns to Rabbi Yisrael Ariel for clarity. Rabbi Ariel explained that the sources that refer to a divinely made Temple are referring to a spiritual Temple in the world-to-come. Rabbi Ariel assures Segal that the prophesied Third Temple in Jerusalem will be built by men.
This is also consistent with Rashi who writes (Ezekiel 43:1) and in the Jerusalem Talmud that it is up to us, humans, to build the Third Temple. What will descend from the sky is the shechina, which will reach the Holy of Holies where the Ark of the Covenant will be placed, then spread throughout the Temple, Jerusalem, Israel, and eventually the rest of the world.
Rabbi Ariel claimed that the concept of Jerusalem descending from heaven in completeness is taken directly from the New Testament as stated by John in Revelation:
I saw the Holy City, the new Jerusalem, coming down out of heaven from God, prepared as a bride beautifully dressed for her husband. Revelation 21:2
“The bottom line is that Jerusalem will not descend from heaven but will be built anew by the great efforts of Man,” Rabbi Ariel said. “It is not proper that the nation of Israel waits for the manifestation of this Christian vision, but, rather, should take initiative to change reality in our Holy City. It is for this reason that more than one million people live in the city, more than ever before in history.”