Herald said:
OT saints were saved based on the future promise of the Messiah but still through regeneration by the Spirit.
No, OT saints did not have the indwelling Holy Spirit. The disciples (except Judas) believed on Jesus, but they did not have the indwelling Spirit, else Jesus would not have needed to promise them he would send the indwelling Spirit.
Jhn 14:16 And I will pray the Father, and he
shall give you another Comforter, that he may abide with you
for ever;
17 Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth
with you, and
shall be in you.
The Holy Spirit did not dwell with OT saints forever, the Spirit could leave a person as he did with king Saul.
1 Sam 16:14 But the Spirit of the LORD departed from Saul, and an evil spirit from the LORD troubled him.
The OT saints did not have the permanent indwelling Holy Spirit. Jesus promised his disciples he would send the Comforter, who would abide with them forever. He pointed out that the Spirit only dwelled "with them" but in the future would be "IN YOU".
Why is this important? Because Romans 8:9 tells us that a person without the indwelling Spirit is a natural man, a person "in the flesh".
Rom 8:9 But ye are not in the flesh, but in the Spirit,
if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his.
If you do not have the indwelling Spirit, then you are a natural man, a person in the flesh.
Yet, hundreds if not thousands of Jews (and some Gentiles) all believed on Jesus without the indwelling Spirit.
Jhn 7:38 He that believeth on me, as the scripture hath said, out of his belly
shall flow rivers of living water.
39 (But this spake he of the Spirit, which they that believe on him
should receive:
for the Holy Ghost was not yet given; because that Jesus was not yet glorified.)
No one had the indwelling Spirit until after Jesus rose from the dead and was glorified, yet many believed on Jesus.
OT saints had to wait in Abraham's bosom until Jesus sprinkled his blood on the mercy seat in heaven and received the promise of the Spirit. Only then did he give the Spirit to believers. Many believe he gave the saints waiting in Abraham's bosom the Spirit and then led them to heaven.
Eph 4:8 Wherefore he saith, When he ascended up on high,
he led captivity captive, and gave gifts unto men.
9 (Now that he ascended, what is it but that
he also descended first into the lower parts of the earth?
Saints did not go to heaven until after Jesus rose from the dead, the prophet Samuel being an example;
1 Sam 28:15 And Samuel said to Saul, Why hast thou disquieted me,
to bring me up? And Saul answered, I am sore distressed; for the Philistines make war against me, and God is departed from me, and answereth me no more, neither by prophets, nor by dreams: therefore I have called thee, that thou mayest make known unto me what I shall do.
As you see, Samuel was not in heaven when he died, he was waiting in Abraham's bosom in the center of the earth as is shown in Luke 16.
Only after Jesus rose from the dead did he give the Spirit to these saints and lead them to heaven. Now all believers go directly to heaven when they die.