Were old covenant believers indwelt by the Holy Spirit? No. They did not need to be. God dwelt in the temple. He was thereby with them. How did old covenant believers become and remain faithful? They became faithful by the regenerating work of the Holy Spirit, which in the OT is described more as ‘circumcision of the heart’ (cf. Jer. 9:25) than as ‘new birth from above’ (cf. John 3:3). They remained faithful not by the Spirit dwelling in them, but by the Spirit dwelling in the temple (Ps. 73:17), where they longed to be (Ps. 116:18–19). Further, the Spirit was active through Israel’s prophets (1 Pet.1:11). As the prophets proclaimed God’s word, the Spirit instructed and admonished God’s people (Neh. 9:20, 30). Under the old covenant, the Spirit gave life and was with the people as he dwelt in the temple. Under the new covenant, the Spirit gives life and dwells in God’s people; they are his temple.
–Jim Hamilton, “Were Old Covenant Believers Indwelt by Holy Spirit,” Themelios (2004), 12-22