The more Christians see the light of Jesus, the more we see the darkness of the world. Every day we are confronted by the effects of Genesis 3 as we encounter human selfishness and idolatry. We are also constantly living in the reality of our own fallen nature and are often tempted by worldly enticements. We are in constant need of spiritual armor for our spiritual battle.
If you've been a Christian for even a short period of time, it's likely you are familiar with the concept of putting on the armor of God. You have most likely found yourself reading about this armor from the commonly referenced passage, Ephesians 6:10-17.
Finally, be strong in the Lord and in the strength of his might. 11 Put on the whole armor of God, that you may be able to stand against the schemes of the devil. 12 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. 13 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. 14 Stand therefore, having fastened on the belt of truth, and having put on the breastplate of righteousness, 15 and, as shoes for your feet, having put on the readiness given by the gospel of peace. 16 In all circumstances take up the shield of faith, with which you can extinguish all the flaming darts of the evil one; 17 and take the helmet of salvation, and the sword of the Spirit, which is the word of God.
This is not the only place where the Apostle Paul encourages the church to put on armor as an intentional focus for our life in this world.
1 Thessalonians 5:8 But since we belong to the day, let us be sober, having put on the breastplate of faith and love, and for a helmet the hope of salvation.
Romans 13:11-12 Besides this you know the time, that the hour has come for you to wake from sleep. For salvation is nearer to us now than when we first believed. 12 The night is far gone; the day is at hand. So then let us cast off the works of darkness and put on the armor of light.
At every reference Paul is telling us to remind ourselves of the spiritual realities we have in Christ so that we can be armed with truth to confront life in a world that is contrary to Christ. Also, Paul seems to be referring us back to the Prophet Isaiah so that we consider who Jesus is as we seek to live in him for the battle.
Isaiah 59:15-20 Truth is lacking, and he who departs from evil makes himself a prey. The LORD saw it, and it displeased him that there was no justice. 16 He saw that there was no man, and wondered that there was no one to intercede; then his own arm brought him salvation, and his righteousness upheld him. 17 He put on righteousness as a breastplate, and a helmet of salvation on his head; he put on garments of vengeance for clothing, and wrapped himself in zeal as a cloak. 18 According to their deeds, so will he repay, wrath to his adversaries, repayment to his enemies; to the coastlands he will render repayment. 19 So they shall fear the name of the LORD from the west, and his glory from the rising of the sun; for he will come like a rushing stream, which the wind of the LORD drives. 20 "And a Redeemer will come to Zion, to those in Jacob who turn from transgression," declares the LORD.
It is evident that the Apostle Paul wants us to know something about the armor he encourages us to wear. God himself will send a Redeemer and he will bring justice to his enemies and salvation to the redeemed. He comes in the armor of righteousness and salvation with judgment and zeal. This armor tells us that Christ is our great warrior. He fights our battles for us. Essentially, Paul is telling us to put on Christ.
If you want to be ready to engage with an anti-God world, put on Christ who is both the Judge of the world and Savior for all who will turn from their sin and trust in Him. Simply put, Christian, if you want to be ready for battle - put on Jesus.