"There were 4 reasons why we were redeemed from Egypt: we did not change our names, we did not change our language, we did not speak lashon hara (evil speech), and not person among them was parutz b'arayot {involved in forbidden sexual activity}." -- Midrash Rabba, Emor
"The Second Temple was destroyed for the sin of causeless hatred, and loshon hara." -- Yoma 9b
"Hakadosh Baruch Hu said; in this world, since there has been loshon hara amongst you, I have withdrawn my shechina." -- Midrash Rabbba, Tetzeh
There are so many hundreds of more quotes like these from our holy Sages (Chazal). The brothers sold Yosef because of Loshon Hara, we wandered 40 years in the dessert because of loshon harah of the meraglim (10 spies). Our first Tisha B'av came from that loshon hara. I know that each of us wants to bring redemption and joy to every corner of the world. Chazal are teaching us that in our own mouths is the power to destroy the house of G-d, or to redeem all of Israel.
So it's simple. Let's just resolve never to speak bad about each other ever again. We'll bring the Moshiach closer with every word we don't speak. . . but it's not so simple. Rav Yisroel Meir Hacohen, the author of the Chofetz Chaim, a comprehensive book on the laws of shmirat halashon, writes in his introduction that there are so many intricate laws, and the desire is so strong, that we all speak it, a little bit, every day. Yet, there is a term used to define someone who speaks continual loshon hara, "a baal loshon hara.' Chazal say some nasty things about this type of person, and we just don't want to share this guys fate, trust me. So the Chofetz Chaim asks, what is the difference between this baal lashon hara and everyone else, who also speak loshon hara every single day? He says the difference is, that someone who is trying, who spends 2 minutes a day learning the rules of shmirat haloshon, even if that person speaks badly, he is not called a 'baal lashon hara.' The implication is that everyone else is a baal loshon hara - scary.
So I am begging everybody, for the sake of the redemption of the world, there are so many books that deal with the rules and meaning of loshon hara. English, Hebrew, Yiddish. Please borrow one from the shul, a friend, or buy one. Please, please learn some chasidut or kabbala about it and go deeper and deeper. I know the holy Reb Nachman says there is not peace in the world because we are not overflowing with joy. And maybe we can only speak bad about each other when we are not so b'simcha (joyous), but until that day, when we are all so joyous that no one even speaks a little bit of loshon hara ever, maybe it would be good to learn the halachot (ways to achieve shmirat halashon).
I bless us all, from the deepest place in my heart, that tomorrow will be Shabbas, forever, that we should accept the Torah on Shavuot together, with one heart, and that this Tisha B'av should be the most joyous celebration for all of Israel.