Host desecration is when someone treats something that's considered holy in a disrespectful way. Some religions have something called the Host, which is a special bread that is used in religious ceremonies. Host desecration would be when someone takes the host and does something to it that is not respectful, like throwing it on the ground or setting it on fire. People do this to try to offend the religious people and show that they don't believe in what the religion stands for.