I heard the following ‘make-you-think-twice idea’ from Rav Osher Weiss…
Both Rashi and Tosfos (sukka) say that the third beis hamikdash will come down from heaven. What are we to do to quicken it? The Sanzer Rebbe (Divrei Chaim) was once in conducting a tisch with his chassidim when he suddenly looked up and announced ‘I see that the beis hamikdash is fully built in heaven and ready to come down – it is just missing a paroches (special curtain).’ One of his chassidim shouted out ‘why don’t you build the paroches Rebbe?’ The Rebbe’s response gives us an insight into effects of our mitzvos… ‘I did build the paroches,’ said the Rebbe, ‘it’s just that some rasha removed it with an aveirah he did.’
Each mitzvah that we do builds part of the third beis hamikdash in Heaven that will come down. This is especially true of learning Torah with love and behaving properly with people (the sins that caused the destructions of the 2 mikdash), and averios that we do [chas veshalom] destroy the bulding of the beis hamikdash in shamayim. Thus, there is a constant battle in shamayim between the builders and destoryers.
Let’s be one of the builders!