And it is my prayer that your love may abound more and more, with knowledge and all discernment, so that you may approve what is excellent, and so be pure and blameless for the day of Christ, filled with the fruit of righteousness that comes through Jesus Christ, to the glory and praise of God
Loving God is tied up in knowing Him. Without a growing knowledge of His character and His actions on our behalf, then we wont be growing in our love for Him. The more we know Him, the more we love Him. They feed each other.
As our knowledge grows, we grow in discernment - the more we know of how God has revealed himself, the more we will be able to discern the real thing, the truth from the lies. As we recognise the truth and accept it, our lives start to look more like Him. The christian life is not supposed to be static but there should be constant growth.
This is sanctification. It is not effort-based "self improvement", it comes from Jesus (v11). It is described as fruit, the natural product, of righteousness (v11) - not our own righteousness, but the righteousness of Jesus, which has been given to us. Why does all of this happen? To bring glory to God, and so that we (and others) will see that glory and praise Him