There is a steady decline in the % of Christianity every year, however, it is only slight. Luckily for religion, Islam is becoming increasingly more and more popular, especially among ethnic groups.
The number of atheists in the world, and when I say atheist, I mean irreligious.(that excludes buddhists and toaists, who also don't believe in god), atheists and irreligious people, account for only at most 5-10% of the world population. The majority of the world is Muslim, followed second by Christianity, then Judaism, and then all the other religions after, with atheism at the bottom of the spectrum.
religion is still on the rise, and while atheism is increasing, it is increasing at a far lower and slower rate than the increase in religious followers, even in such great technological and scientific times.