Much has been hypothesised about this phenomenon. While many rejoice over it as a minus to Christianity , the reverse is indeed the case !

To begin with ; what was the proportion of Christian in the last centuries in London as compared to the present ??

Secondly, in the 18th and 19 the centuries , Britain and other European nations sponsored Christian Evangelists to Africa , Americas etc . This has resulted into exponential growth of Christianity in these Continents , much MORE than the perceived loss being experienced in Europe presently.

Cumulatively , Christianity has grown in all climes of the world much more the previous epochs ! The trend is bound to subsist consistently into the most distant future !!