The work of the Holy Spirit in the Old Testament is seen mainly in three ways: the work of creation, guiding and governing the children of Israel, and in revealing the messianic hope of Israel.
With regard to the work of creation, the Spirit was not only present at creation but was also involved in the work of creation in one of various ways, depending upon one’s view or understanding of the Spirit’s role. Although some try to translate or interpret the word ruach to mean “wind” rather than “spirit,” not all who do so are necessarily attempting to deny the Trinity but are instead trying to understand the work of the Spirit in creation and view reference to the ruach of God as pointing to God in action. It is better, however, to understand the word ruach as pointing to the Spirit as an agent of the Godhead in creation because it fits better with the testimony of the whole of Scripture with regard to the Holy Spirit and his work.
There are three main views of the Holy Spirit’s work in creation. Some understand it to mean that the Spirit is not the agent of creation ex nihilo, but as the ordering agent and so make the Spirit’s role one of continuata creatio. Others see the work of the Spirit as perfecting the causes of creatures to their destinies and so see him more in a conservatio role of directing creation through providence.
Graham A. Cole, in his book He Who Gives Life (in the Foundations of Evangelical Theology series), lists four ways the Holy Spirit related to Israel in the Old Testament: (1) caring for them by providing for them in the Exodus, the subsequent wilderness wanderings and the settlement in the Promised Land, (2) governing them through Moses and the elders in the wilderness, the judges after the settlement in the Promised Land, and the raising up of a king to lead them to deliverance and righteousness (with many of these it is explicitly stated that “the Spirit came upon” them), (3) communicating with them through the prophets, both the speaking and the writing prophets, and (4) in his presence by coming upon those who made the tabernacle (Bezalel) and the temple (David in 1 Chron. 28:12) and by later revealing his continued presence in their midst in the rebuilt temple (Hag. 2:5).
The Spirit also worked in the Old Testament in revealing the Messianic hope. The Branch of Jesse and the Servant of the Lord were both revealed by the Spirit to Isaiah and it was said that the Spirit of the Lord would rest upon them. In Ezekiel 37, the Spirit played a vital role in the prophecy of the recreation of God’s people. Isaiah, Ezekiel, and Joel each prophecy an “outpouring” of the Spirit upon God’s people in the latter days and Isaiah 32 and 44 each prophesy a re-creation through the work of the Spirit.