From MSN:
Even as the overall number of Christians — counted as one group, across denominations — continued to climb to 2.3 billion, the religion’s share of the world’s population decreased by 1.8 percentage points to 28.8 percent, a falloff driven in large part by disaffiliation. The Muslim population, on the other hand, increased by 1.8 percentage points to 25.6 percent, according to the report, which examined changes in religious demographics through an analysis of more than 2,700 censuses and surveys.
“It’s just striking that there was such dramatic change in a 10-year period,” said Pew’s Conrad Hackett, the lead author of the report. “During this time, the Muslim and Christian populations grew closer in size. Muslims grew faster than any other major religion.”