A real theological difficulty can emerge when we read Scripture across the covenants in regard to faith and obedience. On the one hand, Scripture teaches that true obedience flows from faith, and faith itself requires the regenerating work of the Holy Spirit (Rom. 8:7-9). On the other hand, Pentecost is presented as a decisive moment when the Spirit is poured out in a new way (Acts 2:1-4). This raises an unavoidable question: How did Old Testament believers obey God before Pentecost, if the Spirit had not yet been given in this covenant-wide way?
The question matters because it touches justification, sanctification, and the nature of the Old Covenant itself. The answer requires careful distinctions, not a denial of continuity.
The Obligation Never Changed
From the beginning, God has required total obedience. Loving God with all one’s heart and loving one’s neighbor was not introduced by Jesus, but summarized by him from the Law (Deut. 6:5, Lev. 19:18, Matt. 22:37-40). Humanity has always been obligated to obey perfectly because God is Creator and Lord.
Because of sin, however, no one has fulfilled that obligation. “None is righteous, no, not one” (Rom. 3:10). This was true before Christ and remains true apart from Christ.
Israel Was a Covenant People, but Not All Were Saved
This is where much confusion arises. Israel was truly God’s covenant people, yet Scripture repeatedly teaches that many within Israel were unregenerate.
Paul states plainly, “Not all who are descended from Israel belong to Israel” (Rom. 9:6). Moses himself warned that Israel often had uncircumcised hearts (Deut. 29:4). The prophets regularly condemned Israel for having outward covenant privileges without inward renewal (Isa. 1:10-17, Jer. 4:4).
This means covenant membership and salvation were never identical under the Old Covenant. Many were externally part of God’s people but lacked the Spirit and therefore did not obey from faith.
Old Testament Obedience Was by Faith Through the Spirit
Abraham shows what true obedience looked like. He believed God, and it was counted to him as righteousness (Gen. 15:6, Rom. 4:3). His obedience flowed from faith, not moral self-effort. He left his homeland (Gen. 12:1-4), trusted God’s promises, and offered Isaac (Gen. 22:1-12).
Yet his obedience was imperfect. He lied about Sarah (Gen. 12:10-20), feared man, and wavered. This still looks like Christian obedience today: real but still incomplete.
Such faith even in the Old Testament was impossible apart from the Spirit. Scripture teaches that fallen humans do not seek God (Rom. 3:11), and that faith itself is God’s gift (Eph. 2:8). Therefore, Old Testament believers were genuinely regenerated by the Spirit. Abraham’s new heart was real and permanent given by grace through faith.
What Changed After Christ and Pentecost?
What changed was not the necessity of regeneration, but the administration and scope of the Spirit’s presence.
Before Christ, the Spirit regenerated individuals and empowered obedience, but this was not the defining mark of covenant membership. The covenant community remained mixed. The Spirit also came upon individuals for specific roles, such as kingship or prophecy (Judg. 14:6, 1 Sam. 16:13). And in the case of Samson, for example, we’re told the Lord left him. (Judges 16:20)
The prophets promised a future day when God would give his Spirit to all his people and cause them to walk in his statutes forever (Ezek. 36:26-27, Joel 2:28-29). That promise awaited the completion of redemption.
After Christ’s death, resurrection, and ascension, the Spirit was poured out on all believers without exception (Acts 2:1-4, Rom. 8:9). The Spirit now permanently indwells every believer as the defining sign of the new covenant, bearing witness to a finished atonement (Rom. 8:1, 16).
Conclusion
Old Testament believers obeyed by faith through the regenerating work of the Spirit, even before Pentecost. What they lacked was not saving grace, but the covenant-wide, universal, and permanent outpouring of the Spirit that now marks all members of the new covenant.
In addition: 1) The standard of obedience itself never changed, but it is now revealed with greater clarity. Christ exposed the true depth of God’s law, showing that anger violates the sixth commandment, and lust the seventh, so that obedience is understood not merely in outward acts but in the movements of the heart (Matt. 5:21-28).
2) Believers today look back on a finished work rather than forward to promises still unfolding. The death and resurrection of Christ provide a fuller assurance of faith, grounding obedience not in anticipation but in accomplished redemption (Rom. 5:1, Heb. 10:19-22). The Spirit now bears witness to a salvation already secured, not one still awaiting its decisive fulfillment.
Taken together, 1) the clearer revelation of God’s law and 2) the greater assurance that flows from Christ’s completed work fuel Christian obedience with a confidence and zeal that Old Testament believers, though truly saved, were not able to enjoy in the same measure. They obeyed by faith in promises to come. We obey by faith in a redemption finished, with the Spirit given forever to all God’s people.
Adorn the Gospel 