Ok kiddo, so you know who Barack Obama is, right? He was the President of the United States for 8 years. Some people think that he was secretly not a Christian, which is the religion that he said he believed in. They think that he was actually a Muslim, which is a different religion that some people don't like.
Now, why would people think that? Well, some people didn't trust Barack Obama because he was different than most of the other Presidents before him. He was the first Black President, and his middle name was "Hussein," which is a name that some Muslim people have. Some people also said that they saw pictures of him in traditional Muslim clothing or heard him speak in a way that sounded like he was Muslim.
But here's the thing, kiddo: Barack Obama said over and over again that he was a Christian. He also went to Christian churches and talked about his faith. And just because someone wears traditional Muslim clothing or speaks like a Muslim, that doesn't mean that they are actually Muslim - it's just something that some people do for cultural reasons.
So, some people believed that Barack Obama was secretly a Muslim and that there was a conspiracy to hide it from the American people. But there's no evidence to prove that, and it's important to trust what people say about themselves and not spread rumors or lies about them.