In the reformed view of the ordo salutis, the Spirit regenerates, leading to conversion and justification, and then follows the lifelong work of sanctification which ultimately culminates in our glorification (which can be understood as complete sanctification). Evidently, the work of regeneration which leads to our conversion and justification is a work of the Spirit. Similarly, the ongoing work of sanctification, culminating in our glorification, is also a work of the Spirit.
In Ezekiel 36:24-28, the prophet writes these words:
“I will take you from the nations and gather you from all the countries and bring you into your own land. I will sprinkle clean water on you, and you shall be clean from all your uncleannesses, and from all your idols I will cleanse you. And I will give you a new heart, and a new spirit I will put within you. And I will remove the heart of stone from your flesh and give you a heart of flesh. And I will put my Spirit within you, and cause you to walk in my statutes and be careful to obey my rules. You shall dwell in the land that I gave to your fathers, and you shall be my people, and I will be your God."Ezekiel is clear there will come a time when God will give his people new hearts and put his Spirit within them. It seems apparent this had yet to happen at the time of writing and, when it did, this would help God's people to walk in his ways.
Similarly, in John 16:4b-7, Jesus says these words:
"I did not say these things to you from the beginning, because I was with you. But now I am going to him who sent me, and none of you asks me, ‘Where are you going?’ But because I have said these things to you, sorrow has filled your heart. Nevertheless, I tell you the truth: it is to your advantage that I go away, for if I do not go away, the Helper will not come to you. But if I go, I will send him to you."Unless Jesus' is making an arbitrary, or untrue distinction, we must conclude the Spirit [Helper] had not yet come and did not yet dwell in the hearts of believers at the time Jesus was with the apostles. It would appear from Acts 2, the indwelling of the Spirit - as per Jesus' words - followed his ascension.
Jesus teaching in John 3 is clear that one must be born of the Spirit in order to see the kingdom of God. Reiterating this teaching, 1 John 3:24 states "Whoever keeps his [Jesus'] commandments abides in God, and God in him. And by this we know that he abides in us, by the Spirit whom he has given us." John goes on in 4:13 "By this we know that we abide in him and he in us, because he has given us of his Spirit."
The problem is thus: if the reformed ordo salutis is correct, how did believers prior to Christ's ascension come to be regenerate and sanctified if the Spirit, at that time, did not dwell in their hearts?
The dispensationlist has a ready answer to the problem; namely, God works differently across the dispensations. Unfortunately, this view is less tenable than the problem presented to the reformed view. It does not account for the universal nature of Jesus' teaching in John 3 nor John's statements in 1 John. Neither does it account for Abraham's credited righteousness, and the salvation of plethora other characters in the OT, which only ever refer to salvation by faith - belief in a future messiah just as NT believers looked back to a historical messiah.
The tentative answer (to which I am not particularly wedded and of which I am not wholly convinced) seems to lie in the nature of repentance. It is possible God moved individuals to repentance in the OT without dwelling in their hearts. Certainly, our current experience of justification and ongoing sanctification is never complete until our ultimate glorification when we reach Heaven. For OT believers, there could have been a process of justification without the ongoing sanctifying work of the Spirit in their lifetime with sanctification coming simultaneously upon their glorification. Just as there are some further along the road to sanctification than others, but none of us ultimately sanctified until glory, OT believers may have begun and ended their process of sanctification in glory whilst still being justified.
Anyway, thoughts would be appreciated.