I couldn't stand to do more than skim this thread.
It's hilarious to see people dogmatically declaring specific certainties at all, let alone doing so in direct contradiction to each other.
I will join in: I declare with dogmatic certainty that Scripture does not give clear and specific definitions of elder, deacon, pastor, overseer, or evangelist. AFAIK, the only person specifically named as an "evangelist" was Phillip. (Timothy was instructed to "do the work of" an evangelist. Some interpret that as saying he *was* an evangelist, while many opine that he was *not* an evangelist and that was why he had to be instructed to "do the work of" one.) AFAIK, the only person specifically referred to as "pastor" was Jesus (1 Pet. 2:25). AFAIK, the only person specifically referred to as "overseer" was Jesus (1 Pet. 2:25 -- unless we wish to include Judas, Acts 1:20).