Is polygamy a sin?

Polygamy is the oldest form of marriage and was widely accepted in the past but then as civilization progressed it became less of a popular norm. A lot of people still practice polygamy and it’s become a widespread debate on it’s pro’s & con’s. Religiously especially in the Christian faith opinions are divided while many says it’s a sin others doesn’t agree. So we ask for your Vivid Opinion is Polygamy a sin?