Hello Sheng-Ta Tsai, thanks for taking the time to respond.

You said:

"Pew Research gives a different forecast. They predict that the percentage of Christians in the global population will remain the same from 31.4% in 2010 to 31.4% in 2050."

"It is Muslims who are taking over the world. The percentage of Muslims will rise from 23.2% in 2010 to 29.7% in 2050."

Pew's article is good, but it's from 2015, based on data from 2010. The Lifeway article I cited is from 2020, using more recent data.

It looks like Christianity has grown faster, and Islam slower, than the Pew data suggested.

Pew suggested that Christianity would number 2,382,750,000 by 2020. Lifeway shows Christians actually grew to 2,518,834,000.

Pew suggested Islam would number 1,907,110,000 by 2020. Lifeway shows them beneath this, at 1,893,345,000.

Even so, the Pew article agrees with most of these conclusions. It has Islam coming close to Christianity, but not eclipsing it. It sees atheists and non-affiliated declining. It sees the Global South, especially Africa, being the new home of Christianity.

And so on.