When Jesus finished the work He set in motion a permanent change in spiritual leadership.
Whenever leadership switches hands there are changes of some kind. Authority flows from the top down and the tone and philosophy of the leader will trickle down and affect every part of what is submitted under that leadership in some way or another. If that leadership is good then reform happens with resistance. If bad then erosion happens with resistance.
"I will declare the decree: the LORD hath said unto me, Thou art my Son; this day have I begotten thee. Ask of me, and I shall give thee the heathen for thine inheritance, and the uttermost parts of the earth for thy possession." Psalms 2:7-8 KJV
If we look carefully at this passage (quoted in part in Hebrew 1:5) we see that this is not talking about the incarnation (Jesus' Earthly birth) but His session (Jesus' ascension to the throne).
"Long ago, at many times and in many ways, God spoke to our fathers by the prophets, but in these last days he has spoken to us by his Son, whom he appointed the heir of all things, through whom also he created the world. He is the radiance of the glory of God and the exact imprint of his nature, and he upholds the universe by the word of his power. After making purification for sins, he sat down at the right hand of the Majesty on high" Hebrews 1:1-3 ESV
The first Adam, a creation, was passed by and a second man was given a place on the throne. This man was not created. We see the blessing of the first born being given to the second son again and again in the Hebrew scriptures (Jacob is blessed instead of Esau).
The moment Jesus sat down at the right hand of the Father new policies were put in place for everyone under that new leadership. Grace was always God's policy but it was not Adam's policy. Adam was alienated from God. It is Jesus' policy. Now God and man are of the same mind and a man sits on a throne in Heaven.
"David himself, in the Holy Spirit, declared, 'The Lord said to my Lord, 'Sit at my right hand, until I put your enemies under your feet.' ' " Mark 12:36 ESV
The policy maker is in place. Now His policy is reaching into all the places were He has been given authority and there is resistance.
"And even if our gospel is veiled, it is veiled to those who are perishing. In their case the god of this world has blinded the minds of the unbelievers, to keep them from seeing the light of the gospel of the glory of Christ, who is the image of God. For what we proclaim is not ourselves, but Jesus Christ as Lord, with ourselves as your servants for Jesus' sake. For God, who said, 'Let light shine out of darkness,' has shone in our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ." 2 Corinthians 4:3-6 ESV
"And he said to them, 'Go into all the world and proclaim the gospel to the whole creation. Whoever believes and is baptized will be saved, but whoever does not believe will be condemned. And these signs will accompany those who believe: in my name they will cast out demons; they will speak in new tongues' " Mark 16:15-17 ESV
Leadership has changed hands. Adam is no longer in charge. He was given dominion but like Ahab he was a fallen man with evil influences. He is overruled now by a higher authority. Adam never sat on the throne that Jesus sits on. No one else ever has.
No matter what Earthly administration we may fall under. Over the last 2,000 years believers have found themselves in every variety and strange combination. If we are in reform or decline... friendly or hostile... God is our King and we are His ambassadors on the Earth.
An ambassador has the power of delegated authority. That is the power we use in warfare and what makes us salt and light in any place we are assigned to.