I was brought up in a home with parents who are...it's difficult to explain. I was never forced to go to church, the only real time we went to church was a year span between my ages of 12 and 13. I was raised Baptist Christian, and I do believe in God, but I have a more scientific view on reality. Right now, the only way I can explain it is a "God Jesus Intelligent design Old Earth Creation Evolution" horror baby. This can get rather annoying, with a mother asking me to explain 'Theories' on how things work, only to reduce everything I tell her to rubbish. One conversation on a 70 million year old beautiful Ammonite was reduced to an argument over whether or not the earth is 6000 years old, and whether or not Satan tricked humanity into believing the fossil records exists after he killed the dinosaurs when he fell to the earth from Heaven. (Yes, I'm serious. >_>) I've stopped having these conversations. It varies with the subject.
Homosexuality? Parents = It's a sin, bad, going to hell. Me = I don't really care, it's their life choice, free will and all that.
Interracial marriage? (This coming from a Southern - United States point of view) Parents = It's an abomination, they are poisoning themselves, white people are better! If you /ever/ date/marry a (insert other skin color beyond caucasian/nationality), you won't be welcome here. >_> Me = If you love someone/they love you, no matter the race or gender, you deserve to be happy with them.
Other religions? Parents = Why do they believe in all these gods, and worship those weird little statues? Me = ......Because they can? .-.
Yet with all of this, they can be open-minded one day, then the next, as closed-off as a pickle jar.
In all seriousness, it depends on how close-minded the parents are. Yours seem pretty boxed up. Don't try to change them, because you can't change people if they don't want to be. It doesn't matter what truth you teach, if the person isn't willing to listen, then it's as good a point as yelling at a brick wall. Just go along with what they want, but don't let them tell you what you should and shouldn't believe, until you can break free from them and live on your own.