If we keep Jesus’ commandments, we dwell in Him and He dwells in us  -  1 John 3:24

And he that keepeth his commandments dwelleth in him, and he in him. And hereby we know that he abideth in us, by the Spirit which he hath given us.  

To obey Christ is to abide in Him, and those who abide in Him are assured of His abiding presence. The assurance of His abiding presence is the indwelling of the Holy Spirit. All believers have the Holy Spirit, as He is the One who guides them into all truth and enables them to discern error.