Moadim Lesimcha. There is a dispute in the Gemara as to whether Mashiach will be coming on Succot or on Pesach. Therefore, we read the most Messianic Haftarahs on both Succot and Pesach. On the one hand, the world was created in Tishrei, so it would seem appropriate for a "new world" taking place at that time. On the other hand, Nissan was the month of our redemption from Egypt, so that Nissan would be a good time for the final redemption. The Talmud in מסכת עבודה זרה claims that at the time of the redemption, the nations of the world will claim that they were not given a fair chance to show their worthiness to be part of the abundant blessings. Hashem challenges them to see if they could observe the Mitzva of Succah to show their love for Torah. They built Succot but could not tolerate the heat. They kicked down their Succot. Hashem confirmed that even a simple Mitzva like Succah was too hard for them, proving that only the Jewish people were worthy of the Geula.