What can an atheist possibly celebrate?

Yule logs, mistletoe, christmas trees, holly, lighting candles, these all originate from Pagan festivals celebrated long before Christianity. Also, astronomers have calculated the appearance of two planets aligning two thousand years ago above Bethlehem which they think was the star that led the wise men to Christ's birth. However this happened in the middle of June.

Who is the first person giving a speech about how we are the lucky ones to experience life ?

Dawkins

I celebrate every time I have an orgasm. It may be meaningless; but if feels so good.

this sent tingles down my spine. a brilliant video..

This made me proud to be a human

whatever your race, colour or creed

I suggest everyone watch Zeitgeist and Zeitgeist: Addendum.

christians spend what, at least 2 hours, every seven days, for their entire lives, plus holidays and regular prayer

lets see, 365/7 = about 52, plus , idk, 10 days for the extra stuff
62 days a year
average life span about 72 year
62X72 = 4,464, divide by 365 and you get 12

so, christians, waist somewhere close to 12 YEARS of their lives, doing nothing of any importance, idk but you, but i value life enough to want to 12 years, for to attept to enjoy life and make the world a better place

Your math is incorrect. Its more like 312 full days total.

2 x 52 = 104 (hours per year)
104 x 72 = 7488 (hours per lifetime)
7488/24 = 312 (days per lifetime)

<3 Neil deGrasse Tyson