The expression “spirit” without the article described the anointing of the spirit of God after the Day of Pentecost.
Jesus said, “God is Spirit and those who worship Him, must worship in spirit and in truth” (John 4:24)— “He who believes in Me … from his innermost being will flow rivers of living water” (John 7:38).
In the next verse, John comments, “But this He spoke of the Spirit which those who believed in Him were about to receive; for ‘spirit’ was not yet given because Jesus was not yet glorified” (John 7:39).
After Christ ascended, He poured out the spirit of God, and God sent the Spirit of His Son into our hearts.1Galatians 4:6; Ephesians 3:17 Jesus Christ is the Lord in our hearts.21 Peter 3:15 The spirit of God speaks for Christ, gives us power, and keeps us in God’s love.
Paul said, “Having begun in spirit, are you now trying to make yourself perfect in the flesh?” (Galatians 3:3). Jesus likewise rebuked the Ephesians because they had left their first love (Revelation 2:4).
Paul exhorted the Ephesians, saying, “Do not be drunk with wine, but be filled with spirit” (Ephesians 5:18).
To the Romans, he said, “Walk in spirit … You are not in the flesh but in spirit, if indeed, God’s spirit makes its home in you … Those who are led by the spirit of God are the sons of God” (Romans 8:8-9, 14).
And to the Galatians, he said, “If you are led by spirit, you are not under law”—“Walk in spirit, and you will not carry out the desire of the flesh” (Galatians 5:16, 18).
Paul told the Corinthians his message was “in demonstration of spirit and power” (1 Corinthians 2:4)—the power of the holy spirit.
He told Timothy that Jesus Christ was justified in spirit (1 Timothy 3:16)—meaning He received the right to be called a child of God when the spirit of God descended on Him.
After the Day of Pentecost, the spirit of God was described as “spirit” nearly 30 times.