But Seriously Though... (SPOILERS)
This movie doesn't reflect on Christianity or any form of spirituality. This woman clearly had mental issues since the beginning of the movie starting with her flippant and somewhat destructive attitude towards sex. We as the viewers never "hear God" tell her to do anything she creates her own world and uses the christian religion as a vehicle to numb some deeper primary pain that the film never explores. The saddest thing is how towards the end her fanaticism leaves her just as vacant and empty as she was before.
However seriously she was so angry at God for her own actions (she had the free will to not kill her daughter) that she would choose not to go to heaven? And even after killing her daughter she saw her when she (Sharon) "died" so she knew that she ended up being alright. Maybe I'm missing something but I don't understand why she felt that she had the right to be angry? Even after committing that heinous act her child still communicated with her and then she went to heaven, so she was angry about what maybe the thing that drove her to her earlier destructive behaviour? Please someone explain it to me.