Eph 3:14 This is the reason I bow my knees before the Father of our Lord Jesus, the Messiah,
Eph 3:15 from whom every family in heaven and on earth receives its name.
Eph 3:16 I pray that he would give you, according to his glorious riches, strength in your inner being and power through his Spirit,
Eph 3:17 and that the Messiah would make his home in your hearts through faith. Then, having been rooted and grounded in love,
Eph 3:18 you will be able to understand, along with all the saints, what is wide, long, high, and deep--
Eph 3:19 that is, you will know the love of the Messiah—which transcends knowledge, and will be filled with all the fullness of God.
Eph 3:20 Now to the one who can do infinitely more than all we can ask or imagine according to the power that is working among us--
Eph 3:21 to him be glory in the church and in the Messiah Jesus to all generations, forever and ever! Amen.
The word know here is the Greek ginosko. It has many different meanings like perceive, but in this context it is more of an experiential knowing as in 'get a knowledge of perceive, feel'(NT Greek Lexicon Definition 1c). Let's look at the context, "you will know the love of the Messiah(or Christ)-which transcends knowledge[gnosis- knowledge,science], and will be filled with all the fullness(Greek pleroma-completion, repletion, fullness) of God." So putting it together: that you will know and experience the love of Christ-which transcends all knowledge, science, and will be filled with all the fullness[or completion]of God (who will fill you and complete you, and you would be complete with Him).
I want to know how I can be an experiential lover and loved member of the Body of Christ, without being a member that moves from experience to experience without a grounding of love and faith.
Paul through the Holy Spirit here, was wanting first for followers of Christ to have Christ at home in our hearts through faith, then rooted and grounded in love, so then we would experience Christ's love in a super-cosmic way which would make us supra-natural carriers and strategic reformers of this world as kingdom men and women.