If you are still under your parents roof, it would be wise to keep the charade until you can live on your own, I know you feel the urge to be sincere about your lack of belief, but some people have got severe consequences from doing so due to fundie parents.
You should know your parents better than we, so its up to you to evaluate how will they respond to that.
You should know your parents better than we, so its up to you to evaluate how will they respond to that.