The character spouts off stupid lines like:
"Read the Good Book, it calls for blood."
"We want [to kill] the boy."
And from the first trailer the woman who speaks these lines apparently gets a few other morons on her side as well.
Now I can understand having what transpires in the film giving these characters "End Times" ideas, but wanting to sacrifice a child? Give me a damned break... maybe if they were Mayans, for crying out loud. There is no "blood sacrifice" in the New Testament and portraying these characters in such a fashion just chaps my ass.
Having said that, if she turns out to be something other than she seems and is related to what's going on outside, I'll be happy to eat my words.
Aside from that, The Mist just seems like a different version of The Fog but with giant, fake looking CGI bugs.