You cannot see the Holy Spirit. You cannot explain Him. But see His mighty power make the harlot pure, the liar honest, the drunkard sober, the blasphemer pray, and then try to deny the reality of it. It is the work of God by which a poor, lost, guilty, hell-deserving sinner who receives the Lord Jesus receives a new nature, becomes a child of God, and begins a new life. It is a second birth, a spiritual birth.
Physical life begins by birth.
You cannot JOIN the family of God, you must be BORN into it. True, Christians are not made, they are born. A birth is the coming into being of a new life which has the nature of its parents. When you were born the first time, you were made a partaker of the old nature, the sinful nature we all received from Adam. No matter what kind of a religious profession you have made, no matter how good a person you may be morally, unless you have been made a partaker of the divine nature, you are not saved.