"being strengthened with all power according to his glorious might so that you may have great endurance and patience, and joyfully giving thanks to the father, who has qualified you to share in the inheritance of the saints in the kingdom of light." NIV translation
Even our ability to walk in the ways of God does not come from ourselves but is a gift from God. It is only by His power that we have the strength to continue to walk this road. Even in trials, we can be glad and give thanks for the fact that we are His children and a part of the kingdom of light.
"For he has rescued us from the dominion of darkness and brought us into the kingdom of the Son he loves, in whom we have redemption, the forgiveness of sins." NIV translation
Paul reminds us of what we are giving thanks for and that is the forgiveness of our sins that happened because of the blood of Jesus Christ. God loves us because He loves His Son and His Son loved us enough to die for us.
"He is the image of the invisible God, the first born over all creation. For by him all things were created: things in heaven and on earth, visible and invisible, whether thrones or powers or authorities; all things were created by him and for him." NIV translation
Jesus Christ reigns supreme as the very Son of God. He was there at the creation of all things and is the very representation of God. He has all of the authority of the Creator. Paul is reminding the people that it is all about Jesus and the work that He does and not some super knowledge as the gnostics were saying.
"He is before all things, and in him all things hold together." NIV translation
Jesus is not only the Creator but He is the glue that holds everything together. He sustains all life, even those that do not accept Him as Lord and Savior. This is comforting to know in that we do not have to worry about things when we know that Jesus is on the job.