How are we counted worthy to escape the tribulation?

Hi and thanks for the question. It is nice to read that you have read many of the studies! : )

Luk 21:34-36 NASB "Be on guard, so that your hearts will not be weighted down with dissipation and drunkenness and the worries of life, and that day will not come on you suddenly like a trap; (35) for it will come upon all those who dwell on the face of all the earth. (36) "But keep on the alert at all times, praying that you may have strength to escape all these things that are about to take place, and to stand before the Son of Man."

Luk 21:34-36 NKJV "But take heed to yourselves, lest your hearts be weighed down with carousing, drunkenness, and cares of this life, and that Day come on you unexpectedly. (35) For it will come as a snare on all those who dwell on the face of the whole earth. (36) Watch therefore, and pray always that you may be counted worthy to escape all these things that will come to pass, and to stand before the Son of Man."

The majority of versions (see https://biblehub.com/luke/21-36.htm) say to pray and watch that we may have strength to escape all things. Some, notably the KJV and NKJV, tell us to pray that we may be accounted worthy to escape... Unfortunately there seems to be a different Greek word used in the underlying manuscripts leading to the different translations. I'm not qualified to say which is correct. But let's say, for sake of argument, that 'counted worthy' is the correct translation. What then is Jesus saying?

The Context

The context is obviously the return of Jesus which will come, like a trap, upon all those that dwell on the earth. So the context of His statement has the whole world in view. The coming judgement is upon all on this earth. Yet there is an escape! And how important it is to those that dwell on this earth that they are considered worthy to be rescued at this time and are included in this way of escape! So how is one considered worthy by God? You are correct that our worthiness comes through faith in the Lord Jesus. The work of God, according to Jesus, is to believe in One He sent (John 6:29). It is through faith that a person is declared righteous in God's sight (Rom 4:3-6). 

J. Vernon McGee on Luke 31:36 writes:

How are you going to be worthy? The only thing that will make me worthy is my position in Christ. Therefore, I have trusted Him as my Savior, and I have committed my way to Him, so that if I am alive at the time of the Rapture, I'll be going to meet Him in the air by the grace of God.

So why does Jesus tell us to pray that we may be counted worthy? He is emphasizing the importance of making sure we are in this escape. The alternative will be terrible! He is emphasizing the importance of making sure that you are truly born again and a child of God. It is not that some true children of God will be left behind at the rapture. It is that there are 'possessors' of God and there are 'professors' of God. In other words there are those that have the spirit of God and those that simply say that they know God but will be found out on that day. Many of Jesus parables such as the wheat and tares, the parable of the Wedding feast and the parable of the 10 virgins, among others, all have this emphasis on making sure you are truly in the faith and they speak of the division between the true and counterfeit that occurs at His return. 

It is also important, as a true believer, to be watchful and alert in the days in which we live. We want to be found doing our Lord's will when He returns. But this, for a true believer, is related to rewards, not participation in the rapture.   

All true believers are included in the rapture

Now I know that there are some teachers who believe in a 'partial rapture' and teach that only the 'overcoming' Christians will be taken in the rapture while the rest of the body of Christ will be left to go through the tribulation. The Bible doesn't teach this!  

As I have written elsewhere:

You can be sure that when Jesus returns He is coming for His bride. Not part of the bride. He is coming for His body. Not just an arm. The passages that speak specifically about the rapture/our glorification speak of ALL Christians being changed in that day. It tells us to comfort one another with the thought. (1 Thes 4:13-17, 1 Cor 15:51-52) It presents no thought that only some (those holy enough) will be raptured. Both passages say that the rapture happens to ALL believers because all true believers are already overcomers!

For whatever is born of God overcomes the world; and this is the victory that has overcome the world--our faith. Who is the one who overcomes the world, but he who believes that Jesus is the Son of God? (1 John 5:4-5) 

In fact one of those rapture passages, 1 Cor 15:51-52 is, obviously, written to the Corinthian church were Paul tells them that at the rapture 'we shall all be changed.' This is important because the Corinthian church was not one that was 'victorious' or 'overcoming' or even 'holy'. It was in many regards a sinful mess and Paul had to speak very firmly in his letter to them! But it didn't stop Paul saying that they will be in the rapture and nor did it stop him saying that they (the born again believers in Corinth and by extension all true believers) will be 'blameless in the day of our Lord Jesus Christ'. That is how Paul started in his letter to them:

1Co 1:4-8 I thank my God always concerning you for the grace of God which was given to you by Christ Jesus, (5) that you were enriched in everything by Him in all utterance and all knowledge, (6) even as the testimony of Christ was confirmed in you, (7) so that you come short in no gift, eagerly waiting for the revelation of our Lord Jesus Christ, (8) who will also confirm you to the end, that you may be blameless in the day of our Lord Jesus Christ.

So there are many reasons that a partial rapture should be rejected. The fact is that the rapture, where we get our new body and are changed into His image (called our glorification), is as much a part of our salvation (which is all by grace through faith) as our initial justification. You cannot bring works into it any more than you can bring works into our initial justification. It just brings confusion and the glorifying of man, not God. "Salvation is of the Lord." For more information on a partial rapture and why it isn't biblical you could read:
https://www.stempublishing.com/authors/knapp/Rapture.html

I hope this helps. When looking at an important topic like who is going to be raptured, it is important to look at the whole counsel of God and compare scripture with scripture. 

But it is great to read that you are 'anxiously anticipating the Rapture'. So am I! This world is not our home and the longer I live in it the more of an 'alien and stranger' I feel! 

God Bless.