1 Timothy 3:2
ESV - 2 Therefore an overseer must be above reproach, the husband of one wife, sober-minded, self-controlled, respectable, hospitable, able to teach.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
Thanks for your important question. The fact that the Scriptures give the criteria for ones qualifications as "the husband of one wife" indicates that there were polygamists in the church at that time, and in order to prevent them from taking Eldership/ Pastoral position, this criteria was put in place.