Thank you for the question on the Holy Spirit, “Do you have to be a Christian to have the Holy Spirit?”
According to the Scriptures, the Holy Spirit lives within a Christian upon faith in Jesus Christ as Savior and Lord.
The Apostle Paul says this in Romans 9, “9 You, however, are not in the realm of the flesh but are in the realm of the Spirit, if indeed the Spirit of God lives in you. And if anyone does not have the Spirit of Christ, they do not belong to Christ. 10 But if Christ is in you, then even though your body is subject to death because of sin, the Spirit gives life[d] because of righteousness. 11 And if the Spirit of him who raised Jesus from the dead is living in you, he who raised Christ from the dead will also give life to your mortal bodies because of[e] his Spirit who lives in you” (NIV).
Paul states if a person doesn’t have the Spirit of God that person doesn’t belong to Christ. In others words, there are people who do not have the Spirit of God. A believer of Jesus will have the Spirit of God living in him or her.
The transformation of the person’s life begins with the Spirit of God working in that person’s life to come to a point of faith. Upon one’s faith in Jesus Christ as Savior and Lord, the Spirit of God comes and dwells in that person.
Titus 3:5 also says this, “4 But when the kindness and love of God our Savior appeared, 5 he saved us, not because of righteous things we had done, but because of his mercy. He saved us through the washing of rebirth and renewal by the Holy Spirit, 6 whom he poured out on us generously through Jesus Christ our Savior, 7 so that, having been justified by his grace, we might become heirs having the hope of eternal life” (NIV).
In Corinthians 6, Paul states that believer become a temple for the Holy Spirit. He says “9 Do you not know that your bodies are temples of the Holy Spirit, who is in you, whom you have received from God? You are not your own; 20 you were bought at a price. Therefore honor God with your bodies.” (NIV).
There are other verses that speaks on the presence of the Holy Spirit in a believer’s life. There are no verses that speaks of the Holy Spirit indwelling a non-believer. The Spirit as I stated earlier may and will work on a believer, that is upon the believer, but the Spirit does not dwell in that person until she or he comes to a point of personal faith in Jesus Christ.
Summary: The Spirit of God comes and indwells believers who have trusted Jesus Christ as his or her Savior.
-Kingston