If Jesus said that all authority in heaven and on earth was given to Him, who is in charge here?
I'm sure you're using "If" rhetorically, since He did say it (Matthew 28:18), and He said it right after there was apparently some confusion about bowing to Him (Matthew 28:17). So, what's not to believe? He's in charge, and whatever is going on He's allowing, and even facilitating in ways for His reasons. And, with this context, it seems to me that our charge is to make His "all authority" clear to the nations of the world (Matthew 28:19-20)
Re: the adversary as "ruler of this world," verses like these should be considered:
NKJ John 12:31 "Now is the judgment of this world;
now the ruler of this world will be cast out.
NKJ John 14:30 "I will no longer talk much with you, for
the ruler of this world is coming, and he has nothing in Me.
NKJ John 16:11 "of judgment, because
the ruler of this world is judged.
There was a lot of talk elsewhere re: John18:36. Theses following translations should be considered when thinking Jesus' Kingdom is "not
of this world." One of the most straight-forward translations of the Greek word is "from" having to do with source:
NET John 18:36 Jesus replied, "My kingdom is not from this world. If my kingdom were from this world, my servants would be fighting to keep me from being handed over to the Jewish authorities. But as it is, my kingdom is not from here."
CJB John 18:36 Yeshua answered, "My kingship does not derive its authority from this world's order of things. If it did, my men would have fought to keep me from being arrested by the Judeans. But my kingship does not come from here."
There are also some other things to consider re: what has happened:
NKJ 2 Timothy 1:10 but has now been revealed by the appearing of our Savior Jesus Christ, who has abolished death and brought life and immortality to light through the gospel,
NET Hebrews 2:14 Therefore, since the children share in flesh and blood, he likewise shared in their humanity, so that through death he could destroy the one who holds the power of death (that is, the devil),
NKJ James 4:7 Therefore submit to God. Resist the devil and he will flee from you.
Sounds to me like the King is in control and has at minimum taken care of the legal matters re: the above.
And, this is how Paul really evangelized about Christ as can be seen in his reference in Acts of the Apostles 13:33. Here's the link about the coronation of the King of kings - YHWH's Anointed (Christ): Psalms 2.
Also: Acts 2:36 "Therefore let all the house of Israel know assuredly that God has made this Jesus, whom you crucified, both Lord and Christ."
Christ is a title that includes His Kingship.