Jeroboam led a revolt against Rehoboam (Solomon's son), which led to the split of Israel into a northern kingdom ruled by Jeroboam and a southern kingdom ruled by Rehoboam. To help establish his kingdom, Jeroboam decided to change the religious laws (1 Kings 12:25ff). These changes minimized the risk of defections from his kingdom. He set up places of worship and commissioned priests who were not Levites (1 Kings 12:31). Though warned by the Lord about his actions (1 Kings 13), Jeroboam ignored the warning and continued on his path of rebellion against God. Jeroboam commissioned anyone who wanted to be a priest (see below).
After this event Jeroboam did not turn from his evil way, but again he made priests from every class of people for the high places; whoever wished, he consecrated him, and he became [one] of the priests of the high places. - 1 Kings 13:33 NKJV
When authority figures (i.e., commissioning agents) are in rebellion against God, how does one distinguish true commissioning into the will of God and false commissioning into the will of man?