For in him the whole fullness of deity dwells bodily,and you have been filled in him, who is the head of all rule and authority.
Fullness is being completely filled to the full, nothing lacking, complete in the character of God, but not in the nature of God (Eph. 3:19). Fullness is having all that Jesus was and is living in our hearts now. Jesus indwells our hearts by the power of the Holy Spirit and this fullness is available for any need, any ministry, any godly purpose. We lack nothing that we need as live the words of Jesus and trust the Father to perform the works of Jesus.
The fullness of the Holy Spirit is a continuous supply from Jesus Christ himself; a moment-by-moment faith in a moment-by-moment filling and a moment-by-moment cleansing. The moment I begin to believe, that moment I receive, and as long as I go on believing, praise the Lord! I go on receiving.
Charles Inwood quoted in Alan Redpath, “Full of Faith . . .Grace . . . Power,” Keswick Week 1957 (London: Marshall, Morgan and Scott, 1957), 155.