If Jesus is reuniting heaven and earth and transforming this world into the new creation reality of the world that existed before sin and the Fall, then we should not be surprised to discover that Satan, who came to sow chaos into God's good creation at the beginning would come again to sow chaos in among his new creation people.
That is why we, as Jesus’ Church —his body— must put on his armor to make war against the enemy of our souls. But it is not by our strength that we engage in this battle. It is by Jesus —and in Jesus— that we find our hope and strength.
“Finally, be strong in the Lord and in the strength of his might. Put on the whole armor of God, that you may be able to stand against the schemes of the devil. For we do not wrestle against flesh and blood, but against the rulers, against the authorities, against the cosmic powers over this present darkness, against the spiritual forces of evil in the heavenly places. Therefore take up the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand firm. Stand therefore, having fastened on the belt of truth, and having put on the breastplate of righteousness, and, as shoes for your feet, having put on the readiness given by the gospel of peace. In all circumstances take up the shield of faith, with which you can extinguish all the flaming darts of the evil one; and take the helmet of salvation, and the sword of the Spirit, which is the word of God, praying at all times in the Spirit, with all prayer and supplication. To that end, keep alert with all perseverance, making supplication for all the saints, and also for me, that words may be given to me in opening my mouth boldly to proclaim the mystery of the gospel, for which I am an ambassador in chains, that I may declare it boldly, as I ought to speak.”