>>17992754 (OP)
This is a frequent misinterpretation of the data. In actuality, the growth of the atheistic population could largely be attributed to statistical error. It's not atheism, but irreligiosity that "threatens" religions. And this matters because the majority of irreligious people do actually believe in a higher power, see picrel pew research.
Christianity is the largest religion on Earth still today. Atheism is barely making a dent.