Distinguish between the holy and the common

Ezekiel 22:1-31
The Lord pointed out all the wicked things the people of Israel have done.
Dross of copper, tin, iron and silver all will be melted in a furnace(Jerusalem).
Distinguish between the holy and the common.
The people of the land practice extortion and commit robbery; they oppress the poor and needy and mistreat the foreigner, denying them justice.
I looked for someone among them who would build up the wall and stand before me in the gap on behalf of the land so I would not have to destroy it, but I found no one.
Why?
There was not anyone do the right thing in that time.
Dross if waste matter, like garbage, so as they were in present of the Lord.
If there is one who build the wall and stand before God i the gap on behalf of the land, God won't destroy this city or nation, but it is no one there. 
All christian in this generation should be do the mission as the one above.
Have to do something and don't do something as popular matter in these generation.
How?
How can I distinguish the holy an the common? Follow the command of the Lord , under the blessing and reminder of the Holy Spirit, I will surely know what it right and wrong.