Some things are symbolic and some are presented as literal. If something is presented as literal, I wouldn't symbolize it.
I don't think it's possible to decide until we first recognize the larger literary structure of the book. As I already mentioned, the book of Revelation contains three seemingly parallel scenarios. And the gospel is presented in each. Thus, in the first scenario, the gospel as proclaimed by the church is represented as the white horse and rider going forth conquering and to conquer. In the second scenario, the messengers of the gospel are represented by the two extraordinarily powerful witnesses. In the third scenario, again, the church and gospel are represented as three angelic messengers (Revelation 14:6-12).
