"Christ is my life; I have no other life. Christ is all there is in me." "I am crucified with Christ." That's it. It's done, it's finished, it's over with.
There is no me or self that "needs to die." I have no self to die to. Nor does God say anywhere that I should "put my flesh nature to the death on the cross."
I am already dead to sin. That means that I have no connection to sin and sin has no connection to me and that I am already dead, the work of the cross is 100% complete in my life, and if I can also see that I am still alive, all I can do is what Paul does in Galatians 2:20. "Hey, it's not me, it's Christ, only it's me, only it's Christ."
The truth is that Christ living, dwelling and abiding within us is not the end it is just the beginning.
Jesus Christ Himself is our LIVING CONTINUOUS and NEVER ENDING connection to GOD!
The Holy Spirit takes the things of Christ and makes them real to us every second of every day. This does not end.
The Christian life is one of non-ending discovery of the Revelation of CHRIST living WITHIN US us our "only hope of glory.
Galatians 2:20 is not an academic problem or formula to work out, but something to take as absolutely literal fact about ourselves in the present moment, without further explanations, definitions or analysis. We believe Him in a simple acceptance!
If we are in Christ, then we have been crucified with Christ. This is a fact! We did nothing to make it happen. We have been crucified with Christ, period. We don't attain to this; we don't work at it; we don't practice it; we simply take it by faith and believe God that it is so.
This is Jesus' accomplishment, and we are the fruit of His labor! He did it! He made it happen. "This is the Lord's doing, and it is marvelous in our eyes!"
Likewise, "Nevertheless I live, yet not I, but Christ liveth in me," is also literally true in us in this present moment. This is not something we figure out beforehand, like a mathematical formula, what the correct quantities of this and that are, in order to make the formula work. This is a reality which is ongoing in us in Christ, and we trust God that it is so, that He is the one who causes its reality, not by anything we do. We rest in His performance of His life in us, and leave it to Him to give us increasing understanding of Himself in us.
Again, this is something the Lord does, not something we conjure up by right formulas or correctness of words. The Holy Spirit is the One Who testifies of Christ in us, who reveals Christ, and it is not by our rational mind that we comprehend the things of God. The things of God cannot be fully understood in a 1-2-3 logical way as we know the things of this world.
Only God can reveal Himself, and He unveils Himself by the Holy Spirit in our spirits, and not necessarily in a way we can or will understand with our conscious minds. But somehow we just "know," and it is a solid knowing and nothing can shake us from it, even as we know, without any possibility of proof, that we are born again. "He that believeth on the Son of God hath the witness in himself" (1 Jn 5:10).