I appreciate you taking the time to consider this.
I believe it is the antichrist systems throughout this church age since the time of Christ.
Look at it like this. The antichrist and the beast are one and the same. The beast has his image, which is like God and Jesus the Son of God, who is the image of the invisible God. The mark is a mark of ownership, just as the Holy Spirit is our seal and spiritual mark of God's ownership. (Well our down payment of the inheritance until we take material possession. (Ephesians 1))
As far as Nero and the beast, that whole 666 thing is completely wrong. It is his name, not title that is important. Caesar Nero isn't his name. His last name is rather... LONG. Consider that John lived until about 100AD, and didn't mention the name of the beast to ANYONE in coversation. One reason could be that the beast had not been born/come into existence yet. John had no way of explaining who it is.
I still consider Romans 9-11 perhaps 12 to be important in understanding, when you take the Old Testament, such as Zechariah into account. Jesus was sent by the Father to the lost sheep of the house of Israel. NOT to the Gentiles. He was clear when He stated that to the Cushite woman. It is true. At that time, that was where we were in God's plan of redemption. The Jew first, then the Gentile. The Jews rejected the Messiah and He was "cut off with nothing" (Daniel 9); crucified. God said that Israel became disobedient (this speaks of the rejection of the Messiah). By this disobedience, the gospel went out to the Gentiles who became obedient. At the end of time, when the world reaches its end, God will finally come back to Israel and deal with Israel. The remnant that remains within Israel will be saved. By the obedience of the Gentiles, the disobedient Israelites will become obedient again, but only the remnant. If we go with Zechariah, 2/3rds of the people will perish, while 1/3rd will be purged and purified.
Even Jesus spoke of the time of the Gentiles in Luke.
""But when you see Jerusalem surrounded by armies, then recognize that her desolation is near. 21 Then those who are in Judea must flee to the mountains, and those who are in the midst of the city must leave, and those who are in the country must not enter the city; because these are days of vengeance, so that all things which are written will be fulfilled. 23 Woe to those who are pregnant and to those who are nursing babies in those days; for there will be great distress upon the land and wrath to this people; 24
and they will fall by the edge of the sword, and will be led captive into all the nations; and Jerusalem will be trampled under foot by the Gentiles until the times of the Gentiles are fulfilled.
From the rejection of Israel of the Messiah until now, Israel has been under a partial hardening/blindness by God. Evidence of this? Jews are individually being saved today, so salvation is not cut off completely from Israel. Paul says that this hardening/blindness continues
UNTIL the fulness of the Gentiles has come in. That sounds very much related to "the times of the Gentiles" Jesus speaks of. Jerusalem is still not under Israel's control.
Watch what is happening today. If you really want to know if things are going to get really crazy, see if Israel gets the right to rebuild the temple. I wouldn't be surprised if Trump somehow managed to get that connected to ending the war. Perhaps part of adding other nations to the Abrahamic Accords? Granted, that would make Trump the antichrist, but I wouldn't be surprised... Consider he survived an assassination attempt, which to someone who didn't understand may appear to be fatal. It doesn't mean anything, it is just something to add to all the other observations of the day.
