There is often a lot of dismay, particularly on Zig Forums, about the loss of Christianity in the West, and an abandonment of Christ's teachings to us. However, hope is not lost at all, there will always be faithful in the West, but beyond the scope of Europe, Christianity is growing enormously, even faster than Islam. Allow me to explain. Although the Islamic birthrate of 3.0 is slightly higher than the Christian 2.7, there is a massive amount of Muslims leaving the faith, perhaps as high as those joining it. Though it mostly goes unreported in the media, Muslims are leaving Islam in droves due to its lack of spiritual satisfaction, the violence and radical ideologies associated with it, and lack of theological sense. Particularly, this is evident in the Middle East. Here, Iran is seeing a record number of converts to Christianity, as is Algeria and Azerbaijan. The world's largest muslim country, Indonesia, could become majority Christian by 2045 due to the lack of apostasy death punishment for leavign Islam. In Iran and other nations, apostasy is law, which has stifled some growth, but the converts do not fear the Islamic fearmongering. So, which countries will become Christian, and which will cease to be, in the future? Here's my prediction.
To become/gain in Christianity:
And to lose Christian influence/numbers:
As for the US, Italy, Greece, and the Slavic nations, they will stay the same for the most part. Christian influence in the US and Italy may decrease, but they'll retain a large majority. Ancient historic communities of Maronites and Greek Orthodox in Lebanon and Syria, Copts in Egypt, Assyrians & Armenians, etc. will stay the same so long as another Daesh does not surface in the Levant.
Funnily enough, Islam is growing in all the areas where Christianity is weakening, but unluckily for them, Christianity is growing in many of the most 'fortified' Islamic nations. Christianity will grow in Africa and Asia, and Islam will probably grow temporarily in Western Europe, until they too succumb to degeneracy, which is already happening with gay muslim weddings.