Okay, imagine there are different groups of people who believe in God and want to worship Him in their own way. Some people believe that their way of worshiping God is the only "right" way, and that everyone else is doing it wrong. They call their group the "one true church."
Now, these people might go to church every week and read from a special book called the Bible. They might dress a certain way or have rules about what they can and cannot do. They might say that if you don't believe exactly what they do, you won't go to Heaven.
But the thing is, lots of other people have different beliefs about God and how to worship Him. They might go to a different church or mosque or temple, and they might read a different book or wear different clothes. They might say that their way is the only right way, too.
So while some people believe that their church is the "one true church," it's important to remember that there are many different ways to believe in and worship God, and no one way is necessarily better or worse than another. It's important to be kind and respectful to people who have different beliefs than us.