How do we know the Holy Spirit is essential for spiritual life?

The necessity of the Holy Spirit for spiritual life is illustrated in the sermon by comparing spiritual regeneration to the process of the oil being extracted from olives. Just as the olives must be wounded to produce pure oil, Christ was wounded and bruised for our sake, and through His sacrifice, the Holy Spirit is given to regenerate and enlighten the hearts of His people. Without the Holy Spirit, we remain in darkness and unable to produce any light, as our natural state in sin is described as sitting in darkness and in the shadow of death (Psalm 107:10). Therefore, the illumination and transformation that the Holy Spirit provides is crucial for a believer's life.