How to Born Again Before the Resurrection of Christ

Christian Greeting,

Pastor,

I learned that, since after Acts 2, we have lived in the time of Holy Spirit

We can now be born again by Holy Spirit, which is beginning of justification and sanctification

Now, my question is how then the people who had lived before the resurrection of Christ and Acts2 could have experienced newborn without resurrection of Jesus and before Holy Spirit?

More confusing verse is John 7:39

"Up to that time the Spirit had not been given, since Jesus had not yet been glorified."

Then how could the people who lived in OT experience born again without(before) Holy Spirit?

Jesus Christ is same yesterday,today, and forever.(Heb 13:8) and Holy Spirit is also eternal Spirit(Heb9:14)

But this verse seems to divide the time before the cross and after the cross.

And how did the people before the resurrection of Jesus escape from corruption and mortality caused by death in Adam(2Tim1:10;Eph4:22;Heb 6:1; 9:14) even before the resurrection of Jesus?

You also have always emphasized, through the resurrection of Jesus Christ, we can live by His life(Gal2:20;1John3:6); thus righteous and sanctified. Then how about before the resurrection, OT period? Can the newborn be experienced without(before)the resurrection of Christ? Otherwise, it seems unfair.

I believe they were saved by faith also. but my point here is their experience of new born, life of new creation caused by Jesus Christ(2 Cor 5:17)

Thus my question is two,

 1What was the role and work of Holy Spirit during OT time compared with NT time?

 2Are their experience of newborn in the OT same with us even though it was before the resurrection of Jesus?

I'd like to ask this question waiting for your sincere answer. I always appreciate your humble, honest and passion for others in order to save and lead them into Jesus Christ by opening and teaching the Bible correctly and showing us how to live by according to the Bible. Thank you for your guidance. May God bless you always pastor, Kim.