Fundamentally, both of these questions are a confusion between ordo salutis and historia salutis. There is discontinuity between the Old and New Covenant in regards to historia salutis. But there is continuity between them in regards to ordo salutis. In other words in regards to continuity, Old and New Testament believers are saved the same way (grace through faith in Christ alone). What differs is the mode, as Old is faith in the Christ to come in the mode of promises, types, and sacrifices. While New Testament is faith in the Christ that had come in the mode of realization and fulfillment.

Christ gives Old Testament believers spiritual resurrection life by the Spirit, prior to the actual basis of Pentecost in redemptive history. Old Testament believers’ source of spiritual life is the same as NT which is through union with Christ. But now the NT this union is given its consummate bond (union with the exalted Christ) by the realization in redemptive history of Christ’s exaltation. This is to say, the substance of spiritual life is the same in Old and New Testament believers. What differs is the degree or intensity, in that we can say New Testament believers experience the same communion bond in a richer and fuller sense.

In conclusion, I think my questions above was due to confusion between ordo and historia salutis. So what is new at Pentecost is new in regards to historia salutis, where there is an actual basis for Christ outpouring the Spirit onto believers. In regards to ordo salutis, what is new is that there is a richer and fuller working of the Spirit in terms of more people, greater intensity, and different mode.

1) Dr. Gaffin compares the OT to the NT by the way of union with the exalted Christ. Gaffin calls this union a “subspecies” of the fellowship with God. My question is: Who are the OT believers united to? Are they still united to the exalted Christ in some shadowy way, while NT are united to exalted Christ in its consummate form?

2) In regards to the historia salutis, Christ becomes the Life giving Spirit. I have read elsewhere by Gaffin where he says that Life giving Spirit isn’t a timeless description. While affirming that there has been conjoint activity of Christ and Spirit in giving life in the OT. My question is: Does Christ and the Spirit impart resurrection life in a conjoint activity to OT believers, or is the conjoint activity only limited to NT believers only?

Thanks