Because religion is all about indoctrination. When I came out as atheist my dad said that all my ancestors were Christians and I’m stopping that tradition. I don’t care, if they belived that doesn’t mean that I also have to belive and just because it’s a tradition it doesn’t mean it should continue. He also said that goal of atheism is to make people lose their identity (he and many others in my country think that identity is just religious and natinoal identity, they also think that those two things are same). After that I had to explain to him what is identity, how it’s impossible to lose it and that there is no agenda behind atheism.
I said that to him but he doesn’t care because ancestors that lived closer to current time are more important to him.