The shofar is one of the world’s oldest musical instruments. It predates the Jewish people by many centuries. One way you can tell its age is because when the Torah says to blow the shofar, it does not have to explain what it is or how to make it. The Torah assumes that everyone knows what it is.
The original purpose of the Shofar was as a signal to the beginning of a war or battle, like a bugler in the American Civil War. It was the sound of victory after defeating the enemy in war.
Judaism understands that wars against our enemies may be necessary, maybe even inevitable. We can and must defend ourselves and our loved ones. War, though, is never holy. We never rejoice at defeat of our enemies, we only offer gratitude for our ability to live without fear.
In Judaism, we have transformed the shofar as an instrument against our external enemies, and instead as a call the war against our worst instincts, against all the things we do, either on purpose or inadvertently, that may bring pain and suffering to others and to ourselves.
The purpose of the shofar changed from announcing a literal war to a metaphorical one, from destruction of others to improving who we are and bringing peace to the world.
When we blow the shofar at the end of Yom Kippur it signifies the celebration of the attempt to win that war. The internal struggle to do better is never over, but we can at least rejoice in our intentions.
May no one ever again believe that war is holy. May the sound of the shofar open hearts around the world, and change hatred into compassion.