The work of the Spirit in relation to the knowledge of the believer is seen primarily in the witness of the Spirit and the Spirit’s revelation and teaching of the Word.
There is no Scriptural testimony to the Spirit’s role in general revelation or natural theology. Paul explains in 1 Cor. 2:6-13 that the Spirit knows the recesses of the heart, mind, and wisdom of God and makes that knowledge known to human beings. In fact, without the instruction of the Spirit, humans would have no special knowledge of God. Peter makes clear that the Spirit was involved in the prophetic revelation of the OT (1 Peter 1:10-12) and the same passage makes clear the Spirit’s role in the proclamation activity of the NT.
Paul repeatedly claims a prominent role for the Spirit in the proclamation of the Gospel (though mostly with respect to spoken proclamation rather than the written word) especially in 1 Thess. 1:5 where Paul speaks of Word and Spirit in the transformation of the Thessalonian believers. The Gospel of John speaks of Jesus “exegeting” the Father (1:18, ἐξηγήσατο declared, explained, made known) and the Spirit “exegetes” the Son (14:26) and bears witness to him (16:13-17) as “the Spirit of truth” (15:26; 16:13).
The Spirit is also vital to the transmission and preservation of the written Word. Second Peter 1:19-21 makes clear that the Scriptures were not merely the product of men but the men were carried along by the Holy Spirit.
Along these lines, the understanding of the wisdom of the Gospel is also the product of the Spirit, as Paul makes clear in 1 Cor. 1:12-13, by transforming the heart so that one can receive and embrace the truth. While there are no explicit (and undisputed) texts about the Spirit’s role in helping the believer understand Scripture, one may deduce the Spirit’s role from the previously stated passages with the understanding that one can understand the basic message of Scripture without special help, while the receiving of the truth of God does require the work of the Spirit (“welcoming” or embracing,” the δέχεται of 1 Cor. 2:14).
The Spirit also serves to bear witness to the believer’s saving faith in Christ and a seal on the covenant relationship with God. There are several texts that attest to this role of the Spirit (Rom. 8:12-17; 2 Cor. 1:21-22; Eph. 1:13-14; 4:30). The Romans 8 passage is especially important as it gives the Spirit the central role in affirming the faith of the believer.
The understanding that the Spirit also bears witness to the truthfulness of Scriptures is not specifically stated in Scripture but is certainly consistent with the Scriptural witness and may be deduced from certain texts, such as 1 Cor., 2:4-11 that speak of the Spirit’s work of illumination.