That’s the question Kent Parks tackles in his article in the May 2017 Lausanne Global Analysis.

https://www.lausanne.org/content/lga/2017-05/finishing-the-remaining-29-of-world-evangelization#post-107503-endnote-3

Kent does a great job bringing people up to date, introducing movements (to those who might have been living on Mars for the past year and haven’t heard about them), bringing in the biblical passages relevant to the whole subject, then applying key principles that each of us ought to be following. Bravo Kent.