How about I hate that hate that my younger sister is going to church.
Did something happen that makes you hate your younger sisters going to church?
Because I'm agnostic and I find this behavior disgusting
Everyone has freedom of religion and you are wrong trying to force your beliefs on your sisters. You shouldn't judge them because they are your sisters. After all, they don't judge you for being agnostic right?
They should learn the truth, so I'm going to blast my beliefs on them.
Usually people allow others to choose their own religious beliefs.