Is the power and love of God enduring in you? Is your Christian life having results to it? The word "therefore" is referring to the results, conclusions, or applications that are to be in our lives from the reasons given.
The devil wants to get a hold on us so he can attack to discourage and sway us away from God and His ways. Our defense is simple; we are to stand firm in Christ, pray, and allow His work in us and not ours; what we would bring to the table is just fuel for the devil and his ways!
God is calling us to be proactive with our faith so we can grow and be mature. This requires us to be faithful which requires us to submit and to be humble. The result is respect, cooperation, unity, community, and the power of His Fruit at work.
Most Christians ignorantly will state that the law has nothing to do with then since they are under grace. But, according to the Bible, this is not the case!
God does not reject us; rather, it is us who reject Him, He goes out of His way to give us the grace we do not deserve. He gives us His Way, even though we continue to fight against Him by hardening our hearts and rejecting His Truth and precepts.