Sorry to rain on the atheist parade here, but you're ignoring the facts. Religious practices have been around for as long as we have records. There have been atheists throughout the ages as well. If you think that religion is only practiced in isolated pockets of the globe, then you haven't been around much.
Let's examine the 10 most populous countries which account for roughly 60% of the world's population:
1. China: Religion outlawed in 1949 with the advent of communism. Practitioners persecuted, imprisoned, killed. Yet the 1993 edition of Atlas of Religion finds only 10-14% of Chinese citizens consider themselves atheist. In 2007, China passes a statute recognizing religion as an important element of citizens' life.
2. India: Hinduism alone accounts for 80% of the population. Islam and Christianity make up another 15%. There are various smaller religious groups as well.
3. USA: 15% of US adults identify themselves as "no religious affiliation"--only a portion of these consider themselves atheist.
4. Indonesia: 85% Muslim, 9% Christian, plus Buddhist, Hindus.
5. Brazil: 74% Roman Catholic, 15% Protestant, 3% other.
6. Pakistan: 97% Muslim.
7. Bangladesh: 83% Muslim, 16% Hindu
8. Nigeria: 51% Islam, 48% Christian
9. Russia: Soviet Union had an ideological objective of elimination of religion for decades under communist rule. Despite this, Russians self-identify as 70% Russian Orthodox, 6% Muslim, 1% Protestant.
10. Japan: Tough call--if you include Buddhism/Shinto as a religion (vs a philosophy.) If not, roughly 55-65% do not believe in god.
Those numbers do not describe a movement toward atheism that you seem to envision (only Japan has a minority of religious adults.) In fact, given the examples of China and Russia where people had every incentive NOT to practice religion, it argues to the contrary.
