God does not zap people with the Holy Spirit and make them Christians as Calvinist believe. Nor does God give his Holy Spirit to those who do good works such as Catholics.
Paul said to the Galatians, "This only would I learn of you, did you receive the Spirit by the works of the law (Because you did something) or by the hearing of faith? ( Hearing the Gospel) Galatians 3:2.
The Holy Spirit is given to those who hear and believe the Gospel.
The minute that one hears and believes the Gospel God seals them with the Holy Spirit and places them "In Christ".
"In whom you also trusted after you had heard the word of truth, The Gospel of your salvation: in whom after that you believed you were sealed with the Holy Spirit of promise" Ephesians 1:13.
God only gives his Holy Spirit to those whom he sees as perfect and complete "In Christ", Colossians 2:10.
The Gospel is the entrance into eternal life. God's mark of ownership is the Holy Spirit. In the judgment you will be identified by the Holy Spirit. If you are void of the Holy Spirit you are lost.
WHAT IS THE EVIDENCE OF THE HOLY SPIRIT?
Good works are not evidence that one is indwelt with the Holy Spirit. Many are trying to work their way into heaven by their works or by being good enough.
Those that are indwelt with the Holy Spirit testify of Christ, John 15:26. They teach and preach the Gospel and are witnesses for Christ in what they say, do and believe. They are Christians.
They do not speak of themselves, John 16:13. Religious people are always talking about themselves and their religion. The Gospel is not about us, the Gospel is about Jesus Christ.
They glorify Jesus Christ, John 16:14. Christ is glorified when the Gospel is preached. The religious glorify themselves. Religion is subjective, The Gospel of Jesus Christ is objective (outside of us).