I will start by telling us that there is no Christianity without the Holy Spirit.
The scripture says that those led by the spirit are the sons of God. Therefore any life that is not led by the Holy Spirit, that life is in grave danger.
Key Points
The holy spirit is God in Trinity; God the father, God the son and God the holy spirit.
The holy spirit is a mark of ownership as a child of God.
Works of the Holy Spirit
The holy spirit gives us power to be a child of God (John 1:12)
The holy spirit gives us boldness (Acts 4:7-10)
The spirit of God is creative (Genesis 1)
Note: If we are not careless with dealings and how we talk, we can create life.The word of God is spirit and life.
Conclusion
We need the holy spirit as Christian and when we receive this spirit, may God give us the grace not to grieve the Holy Spirit by which we were sealed unto the day of redemption.
Stay Blessed.!