Deicide means the act of killing a god. Let's say you have a superhero action figure, and you play with it every day. That action figure is like a god to you because it's super strong and can do amazing things. Well, deicide would be like taking that action figure and destroying it completely, never being able to play with it again.
In ancient times, people believed in lots of different gods and goddesses who controlled different aspects of life. They built temples and made offerings to these gods to keep them happy and avoid their wrath. But sometimes people got mad at these gods for not helping them in times of need or for punishing them too harshly. In extreme cases, they might want to kill the god they believed had wronged them.
However, deicide isn't a real thing because gods aren't living beings like us. They are usually seen as eternal and all-powerful, so you can't just kill them. Plus, deicide is considered a terrible act and is likely to upset many people who worship that god. It's important to remember that different religions have different beliefs, and it's essential to respect those beliefs, even if they are different from our own.