I have located 4 marriage records from the "U.S. and International Marriage Records, 1560-1900" collection on ancestry.com that link a Robert Poage and an Elizabeth Preston together. Each has the option to order a copy of the original document from a place called Vital Check, but I haven't done so. Of course, with any of these types of records they could be completely inaccurate.
I would be interested in your information about Elizabeth Rennick/Renick if you are willing to share.
I do travel through this area of Virginia fairly often and plan to stop and visit the church in person later this summer.