Tisha b'Av, commemorating the destruction of the temple, is this weekend. (Shabbat is the actual date, but we don't mourn on Shabbat so the fast and other observances are pushed off to Sunday.) The talmud in tractate Gittin is relevant.
The g'mara starting on 55b says that the destruction of Jerusalem came through a Kamtza and a Bar Kamtza. How so? A certain man had a friend Kamtza and an enemy Bar Kamtza. He made a party and told his servant to bring Kamtza, but instead the servant brought Bar Kamtza. When the man saw his enemy he said "what are you doing here? Get out!" Bar Kamtza replied, "since I am here, let me stay and I'll pay for whatever I eat and drink", but the man said no. "Then let me give you half the cost of the party" -- no. "Then let me pay for the whole party" -- and still the man said no, and took him by the hand and put him out. Bar Kamtza then reasoned: the rabbis were there as guests and saw all this but did not stop him, so they must agree with him. I will go and inform against them.
So he went and said to the emperor: the Jews are rebelling against you. "How can I tell?" the emperor asked. Bar Kamtza said: send them an offering and see if they will offer it on the altar. So the emperor sent a fine calf, but on the way Bar Kamtza made a small blemish on it so it would not be an acceptable offering under Jewish law. The rabbis were inclined to offer it anyway to avoid giving offense, but R. Zechariah b. Abkulas said this could mislead Jews about proper offerings. They then proposed killing Bar Kamtza so he couldn't inform against them, but R. Zechariah asked: is making a blemish a capital offense? R' Yochanan then said: through the scruplulousness of R' Zechariah our House has been destroyed, our Temple burnt, and we have been exiled from our land. (55b-56a)
The rabbis say that the second temple (the one being talked about here) was destroyed because of sinat chinam, baseless hatred within Yisrael. This episode with Bar Kamtza illustrates the problem; it's not that the temple was destroyed because of this specific incident, but that this behavior was considered normal and acceptable -- none of the witnesses acted. If we can't treat each other decently, maybe we don't deserve the temple and the land.