So basically, there are some bad people in the world called ISIS or ISIL. They don't like Christians, a group of people who believe in Jesus and worship God.
ISIS is hurting and killing lots of Christians because they don't want anyone to believe in anything other than what they believe in. They are doing really bad things like burning down churches and kidnapping people.
It's kind of like if you had a friend at school who loved pink, but then another kid came and said that anyone who loved pink was bad, and started to hurt them. That's not fair, because everyone should be able to like whatever they want, and everyone should be treated with kindness and respect.
So it's really important to help the Christians who are being hurt by ISIS and to stand up for what's right. We all have the right to believe in what we want and live in peace.