So - What do you think abut this growth?
This is a litmus test issue, because of the nature of the churches that are growing - on the whole this massive growth is among what is termed 'Renewalist' churches - that it to say Pentecostal and Charismatic churches.
What distinguishes this low church Protestant tradition is therefore a perspective which emphasises a renewal of the person following (but not usually simultaneous with) conversion - as evidenced by what may be termed gifts of the Holy Spirit.
In the case of Petecostalism, there is the focus on speaking in tongues, but the worldwide phenomenon is not so tightly defined - a range of gifts are recognized and important such as healings, prophecy, miracles, visions - all manner of what might be termed 'supernatural' evidences.
In Africa, this work of the Holy Ghost and a life of faith is apparently often linked to worldly success - health, happiness, prosperity, marriage, children etc. These are taken to be the rewards of faith and also evidence of faith.
This world phenomenon ought to make Western Christians confront the nature of their own faith.
Is this growth of Christianity something to be celebrated by Western Christians, despite that it is happening among churches and people who - if they were located in the West - would be regarded with dismay, and indeed strongly disapproved of, by most Christian commentators from most of the major Western denominations?
In a phrase: is the actual worldwide growth of Christianity A Good Thing, or not?
This question leads onto a consideration of who counts as a Christian - or more exactly, when is identifying as a Christian beneficial, and when is it harmful (it could hardly make no difference at all!). National surveys focus on 'self-identified' Christians - yet no actual serious Christian believes that everyone on the world who says (or claims) they are 'A Christian' really is one.
(Many mainstream Christians would not regard me as a Christian, after all, since - although I am not a member of the CJCLDS - my beliefs are Mormon. They must them decide whether Mormon Christians are, on the whole or in my case, a good albeit imperfect thing, or a bad and dangerous thing. Assuming my beliefs 'make a difference' to me and my behaviour - they must surely be one or the other - beneficial or harmful.)
My impression is that people distinguish between a type of Christianity that is appropriate for African or Chinese in their own nations - and what is appropriate for the West, so they can celebrate growth of types of Christianity in other places that they would argue vehemently against in the West. But with unprecedented world population movements this attitude may not be viable - aside from the fact that it seems evasive to the point of dishonesty.
The question Western Christians need to ask themselves - from their perspective as devout and serious Roman Catholics, Lutherans, Baptists, Anglicans, Orthodox, or from being a Jehovah's Witness, a Mormon or whatever - is whether they personally would approve of a Western Christian revival IF it was of the same type as actual recent and current Christian growth in other parts of the world?
If Pentecostal and Charismatic churches of many shapes and sizes began to spring up in The West with a focus on personal supernatural experiences - if these churches changed people's lives, lent them enthusiasm, courage, energy... would you be pleased, or dismayed?
Because such a phenomenon could not be a matter of indifference. Sooner or later you, like everyone, would need to take sides and decide: Are such Christian churches to be encouraged, or suppressed?
This makes a valuable, and educative, thought experiment - one from which you might learn something about yourself and your faith - and maybe even change yourself.