Okay, so imagine that a long time ago, people believed in God and Jesus in a certain way. They had their own rules and traditions for how to pray and behave in church. But then, some people decided to change these rules and do things in a different way.
These new rules were called "reforms," and they became popular in many places. However, some people didn't like these changes and wanted to keep doing things the old way. They thought the changes were wrong and weren't true to what God wanted.
In Latvia, there were a group of people who were very devoted to the old ways of doing things. They were called "Old Believers." These people believed that the reforms were bad and that they needed to keep following the old traditions in order to stay true to God.
The Old Believers became a sort of separate group from the other people who went to church. They built their own churches and had their own priests who followed the old traditions. They even had their own special clothes that they wore to church.
Even though the Old Believers were different from the other people, they still believed in God and Jesus just like everyone else. They just had their own way of doing things. Nowadays, there are still some Old Believers in Latvia who follow the old traditions and keep their faith strong.