How do we know the Comforter is essential for Christians?

In John 16:7, Jesus tells His disciples that it is 'expedient' for Him to go away so that the Comforter can come. This indicates that the presence of the Holy Spirit is more beneficial for believers than even Christ's physical presence would have been. After Christ's ascension, the Holy Spirit was sent to empower and guide the church, filling believers everywhere and allowing them to exhibit His power in a way that Christ’s physical body could not. The indwelling of the Holy Spirit highlights the importance of this divine presence in the life of a Christian, reminding us that it is through the Spirit that we experience Christ and fulfill His mission on earth.