In his sermon, "Loosing My Religion - Why Christians Should Drop Their Religion", Dr. Timothy Keller uses definition of religion similar to that of Jefferson Bethke...or vice versa. It is no wonder Bethke looks up to Keller.
Keller attempts to support his point by stating that the word "religion" which originates from Latin, has no positive light in the Bible, except for James 1:26-27.
I am not sure how he did his research. Perhaps he only wishes to convey his point regardless of accuracy. The Vulgate Latin use of "religio" is found everywhere in the Bible both Old and New Testaments which sometimes means "devote", "worship", etc.. Sometimes God's ordinance is uttered as religio when translated to Latin (Exodus 12:43).
I believe Dr. Keller's attempt to reach out to the so called "seekers" group has gone too far. Watering down the true definition of the word "religion". It a cheap shot at attacking the extreme conservatives.
If he was referring to "θρησκεία", it is a different topic and therefore a desperate invalid argument.