Hi.
It's really frustrating to have someone else's viewpoints imposed upon you. Sometimes it takes awhile--longer than you'd like--to get parents to accept your views.
In this case, your parents have probably been assuming your life would turn out like theirs did. You'd go to church, have a religious wedding and raise your kids as they raised you. At the base of these expectations is the notion that you also would believe in the basic tenets of their faith.
I'm quite sure your atheism deeply upsets their worldview. Their denial may be their way of dealing with being thrown off-kilter, but it won't last forever. Try to be patient with them.
Eventually, your parents will realize they cannot force you to believe in anything. Living with them might be stressful during this adjustment period--they may try to pressure or force you to go to church or participate in religious ceremonies, for example. Because you are living in their house, you may have to "play by their rules" for the time being, which may not be easy for you.
In the meantime, you may wish to look around online for support groups for atheists (a good place to start is right here on the Atheism folder). Talking with others who are in a similar situation may help you to cope with your circumstances. Speaking with friends who feel as you do may also help.
As you grow older, you will become less dependent on your parents and can make your own way in life.
