All people are children of God, and the Spirit of God resides within them. However, God’s Spirit is usually in the state of a sinner, under the control of the devil.
The Bible teaches that salvation is attained only through being born again by the Holy Spirit. The Holy Spirit, which leads to salvation, is the Spirit of God that overcomes the “self,” the spirit of the devil that destroys life.
The Holy Spirit cannot come upon sinners. When the Spirit of God within each person grows stronger and stronger, becoming the powerful God who overcomes self (the devil = the power of death), then God Himself becomes the Holy Spirit, the resurrection of God, the gift of God—faith—and the spirit of the old self becomes a martyr.