There is good news and bad news. The good news, for us, is that by 2035, the non-religious will face a birth dearth, and begin the descent to extinction. Great! But, the bad news for Christians is that babies born to Muslims will outnumber babies born to Christians:
http://www.pewforum.org/2017/04/05/the-changing-global-religious-landscape/
https://theoutline.com/post/1353/there-is-no-such-thing-as-a-muslim-baby?zd=1&zi=vc4al4so
“More babies were born to Christian mothers than to members of any other religion in recent years, reflecting Christianity’s continued status as the world’s largest religious group. But this is unlikely to be the case for much longer: Less than 20 years from now, the number of babies born to Muslims is expected to modestly exceed births to Christians, according to new Pew Research Center demographic estimates. Muslims are projected to be the world’s fastest-growing major religious group in the decades ahead, as Pew Research Center has explained, and signs of this rapid growth already are visible. In the period between 2010 and 2015, births to Muslims made up an estimated 31% of all babies born around the world – far exceeding the Muslim share of people of all ages in 2015 (24%). The world’s Christian population also has continued to grow, but more modestly. In recent years, 33% of the world’s babies were born to Christians, which is slightly greater than the Christian share of the world’s population in 2015 (31%).”