Good questions. You are making me think!
The qualification from the human side is the same after the cross as before the cross. For salvation, there must be faith. Thus, we have that whole wonderful chapter of Hebrews 11, detailing many who had faith before the cross.
This is a tough one. I'll say that the LXX has μου, actually meaning "my" rather than "his." Using "my" makes it particular to that individual. So the NT writers left that out under the inspiration of the Holy Spirit to generalize the statement, and show that all must come by faith, not just Habakkuk. The NT writers did similar things in other passages to correct the LXX, which is a somewhat spotty translation.
We must have faith for God to justify us. This is true in both the OT and the NT eras. It has always been true and is true today. Note the following verses:
Rom. 3:28 "Therefore we conclude that a man is justified by faith without the deeds of the law."
Rom. 5:1 "Therefore being justified by faith, we have peace with God through our Lord Jesus Christ:"
Gal. 2:16 "Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified."
Gal. 3:11 (which you already noted) "But that no man is justified by the law in the sight of God, [it is] evident: for, The just shall live by faith."
Gal. 3:24 "Wherefore the law was our schoolmaster to bring us unto Christ, that we might be justified by faith."
Your thoughts to the following. My note/thought in [ ].
YLT Romans 5:19 for as through the disobedience of the one man, the many were constituted sinners: so also
through the obedience of the one, ['Father, to Thy hands I commit my spirit;'/ having become obedient unto death -- death even of a cross] shall the many be constituted righteous. [just/justified]
Now I contend that obedience, of one, is the. obedience of faith, a phrase found twice in the NT and that faith being the faith of Christ and was the faith that came spoken of in Gal 3:23-25, the faith
of Christ. And here is why I contend that to be so.
The obedience .....................
Hebrews 5:7,8 YLT who in the days of his flesh both
prayers and supplications unto Him who was able to save him from [out of] death --
with strong crying and tears -- having offered up, and having been heard in respect to that which he feared,
through being a
Son,
did learn by the things which he suffered --
the obedience, If that is not the obedience of faith then please tell me what is being described here. It was through the faith of Christ that he was raised from the dead and given glory through which the Holy Spirit came to be to indwell. See John 7:39 and this he said of the Spirit, which those believing in him were about to receive; for
not yet was the Holy Spirit, because Jesus was not yet glorified. John 17:5 'And now,
glorify me, Thou Father, with Thyself, with the glory that I had before the world was, with Thee; 1 Peter 1:21 who through him [Jesus]
do believe in God,
who did raise out of the dead, and glory to him did give, so that your faith and hope may be in God.
I believe it is the faith of Christ that is imputed not anything we think or of ourselves believe. I believe God the Father through the Son of God gives to the ones called the Spirit of Truth unto belief.
Now Consider the following verse in that context.
having known also that a man is not declared righteous by works of law, if not through the faith of Jesus Christ, also we in Christ Jesus [By the gift of the Spirit of Truth]
did believe, that we might be declared righteous [Just] by the faith of Christ, and not by works of law, wherefore declared righteous by works of law shall be no flesh.' Gal 2:16 YLT with my notes
It also applies perfectly with all your verses quoted in thread 145