What is the origin of the idiom "separate the sheep from the goats" and when to use it?

The idiom "separate the sheep from the goats" has its roots in biblical and agricultural references. The phrase comes from the Gospel of Matthew in the Bible, where it is used metaphorically to describe the act of distinguishing or separating the righteous (symbolized by sheep) from the unrighteous or inferior (symbolized by goats). Figuratively, it is used to refer to the differentiate between two groups or individuals based on their qualities, characteristics, or merits.