This prayer is not for cerebral or secondhand knowledge, but that the believers would truly and personally comprehend the love of Christ. “But God demonstrates his own love for us in this: While we were still sinners, Christ died for us” (Rom. 5:8). The immensity of redeeming love surpasses knowledge and can only be known through experience. Whitney Houston was a great singer, but “learning to love yourself” doesn’t come close to touching the real “greatest love of all.”
The experience of true believers goes beyond mere religion. We are filled with the supernatural fullness of God and the fruit of the Sprit. We can be so filled with God that there is no room for sin to gain a foothold in our lives.
Now when it says you are filled up with the fullness of God, it doesn't mean you become God. It simply means that the essence of who God is in His glory is going to be filling your life. If I go down to the Pacific Ocean, I take a little glass and I scoop up some of the ocean, it wouldn't be proper to say that the entire Pacific Ocean is in my glass because there's much more. It is vast and vastly beyond my glass. All of the ocean is not in my glass but… the ocean is in my glass. The essence of what it is is contained there. And all of the vast infinity of God is not in me but what God is by virtue of His nature is in me. And I become like Him, moving, as 2 Corinthians 3:18 puts it, from one level of glory to the next to the next to the next. – John MacArthur