Christianity is a dying religion, the vast majority of chrisitians are only christians by name.
This is true. I think Christianity will make a comeback, though.
We know that at the end of time there will be Christians, they will fight alongside Muslims against a common enemy and the Christians will say something like "the cross has prevailed".
Hadith of the Prophet Muhammad (saws) in English and Arabic
sunnah.com
So clearly there will be Christians and they will religious Christians rather than just cultural Christians.
How will this be the case? My theory is the West will collapse, the population will become more religious but they will go back to Christianity rather than becoming Muslim. I think they will have a revival and become more religious sort of like how some of the Muslim countries have become more religious after previously being more secular.