"Live in the Spirit "

is to,
Live in the Holy Spirit; to abide in Him, make one's home in Him, remain in Him.
By the indwelling or filling of His Holy Spirit, we "sit together in heavenly places in Christ Jesus".

But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith, Meekness, temperance: against such there is no law. And they that are Christ's have crucified the flesh with the affections and lusts. If we live in the Spirit, let us also walk in the Spirit. Galatians 5:22-26

But God, who is rich in mercy, for his great love wherewith he loved us, Even when we were dead in sins, hath quickened us together with Christ, (by grace ye are saved;) And hath raised us up together, and made us sit together in heavenly places in Christ Jesus...
Ephesians 2:4-6