How do we know the Holy Spirit's work is necessary for Christians?

The necessity of the Holy Spirit's work is founded on the biblical understanding of human depravity due to the fall. Scripture tells us that a dead soul cannot comprehend spiritual truths or have a relationship with God without the Spirit's active regeneration. This regeneration is not merely helpful but essential; without it, one is incapable of gaining spiritual life or understanding the truth of God as revealed in Jesus Christ. As emphasized by the Apostle Paul, believers are washed, sanctified, and justified not only by the work of Christ but also by the Spirit of God, highlighting the dual roles essential for salvation.