Hamartiology is a big word and it means the study of sin. You know how sometimes you do things that are not very nice or hurtful to other people? Those things are called sins.
Hamartiology is when grown-ups try to understand why people make bad choices and what they can do to make better choices. It is important to learn about hamartiology because it helps us to become better people and make good choices. Just like how we learn to be kind and share our toys, hamartiology helps us to learn what is right and wrong so that we can make better choices in the future.