1. There's a lot of creationists who aren't Christian. It just looks like there are because the non-Christian publishing companies won't publish anything hinting at creationism, because they think it's a religious thing.
Do you have any idea what you just said? Creationists are specifically Christian!* Because they believe in the Abrahamic (e.g. Christian) creation story of the Abrahamic God (e.g. again, Christian) creating the Earth!
That would be like, like... Like saying that there are a lot of non-Christians who believe in God and Jesus is the savior! That makes no god damn sense! Or like being born, raised, and speaks natively German doesn't make you German!
*Or I suppose Jewish or Muslim, as they all honor the same God and his creation of the Earth. But since most people in the US are Christian, I'm using Christian as a pseudo-umbrella term.