Why do so many atheists...

Why do so many atheists get married in Churches, with white dresses? Why do they follow the traditional route with funerals?

Also why do so many keep biblical values like no sex outside of marriage and other dictated values? Plus also judge people harshly for things like polygamous marriages? Or same sex partnering? Or even just threesome marriages.

If you didn’t use a traditional wedding i.e. white dress or a traditional funeral what other things did you do to stand up for your own beliefs?

This is a curious question about atheists ways of doing things not a religious question.