Timothy 3: [1] A faithful saying: if a man desire the office of a bishop, he desireth a good work. [2] It behoveth therefore a bishop to be blameless, the husband of one wife, sober, prudent, of good behaviour, chaste, given to hospitality, a teacher,
This passage has nothing to do with polygamy. In the early Church, many of the men that were called to be Bishops or Priests were married with families. I think what Paul is referring to, is that if anyone feels called to be a Bishop, he should not have any previous wife that he has ‘put away’ through divorce. That’s based on what Jesus taught about divorce being a sin. A Bishop that was married to a new wife, after being divorced, would cause a serious scandal in the Church, so all Bishops needed to be good examples of Christian virtue. It wasn’t until many years later that celibacy was required of the Priesthood.