The bible talks about 1⁄3 of the population dying  Is that after the antichrist is in power?

The 200 million soldiers marching across India killing everyone as they seek to invade Israel .

Revelation is all about Jesus' judgment and destruction of ancient Rome, the capital of Satans earthly kingdom. Most its content transpired during the dark/middle ages of history. The bubonic plague that GOD sent as one of her 21 curses wiped out a third of the population of that time. 

https://www.history.com/topics/middle-ages/black-d...

The antichrist you speak of refers to the early papacy of that time. 

We hold upon this earth the place of God Almighty.

Pope Leo XIII

"The Pope is not only the representative of Jesus Christ, He is Jesus Christ himself, hidden under the veil of flesh.” 

If you want to see all the prophecies of Revelation fulfilled, then study the fall of the Roman Empire.

Pope Nicholas I declared: "The appellation of God had been confirmed by Constantine on the Pope, who being God, cannot be judged by man.”

(Labb IX Dist.: 96 Can 7 Satis Evidentur Decret Gratian Primer Para)

"All names which in the Scriptures are applied to Christ, by virtue of which is established that He is over the church, all the same names are applied to the Pope.” 

On the authority of the Councils, book 2, chapter 17

The popes are all antichrists.

The "one world government" that caused the biblical "great tribulation" was the ancient Roman Empire.

ITS ALL.OVER AND DONE WITH GUYS!

during what will be called the Tribulation period

That falls into the final 3 1/2 years of the 7 year time frame of the Great Tribulation, when Antichrist is publicly revealed.

If you read through the book of Revelation (using the idea that these are future events that will fulfilled at the very end of time) you will find there is more than one plague that takes out "1/3" of the population.  Some happen before the sections that talk about the anti-christ.  Others happen afterwards.  

Many are deceived and at the 6th trump, Satan comes.  They will think i is t Christ and will follow him.  Christ comes at the 7th trump.  He will be returning to gather his people.  Nothing says that it will be half going with either.

The bible is a plagiarized work of bad fan fiction, displaying woefully stupid claims and absurdly BAD morals.

Yes.