To put on the whole armor of God is to simply trust in Christ.
Finally, my brethren, be strong IN THE LORD and in the power of HIS MIGHT. Put on the whole armor of God…
Stand therefore, having girded your waist with truth, having put on the breastplate of righteousness, and having shod your feet with the preparation of the gospel of peace; above all, taking the shield of faith with which you will be able to quench all the fiery darts of the wicked one. And take the helmet of salvation, and the sword of the Spirit, which is the word of God;
Ephesians 6:10-11, 14-17
Now look at who’s wearing it.
For HE put on righteousness as a breastplate, And a helmet of salvation on HIS head; HE put on the garments of vengeance for clothing, And was clad with zeal as a cloak.
How beautiful upon the mountains Are the feet of HIM who brings good news, Who proclaims peace, Who brings glad tidings of good things, Who proclaims salvation, Who says to Zion, “Your God reigns!”
And He has made MY mouth like a sharp sword; In the shadow of His hand He has hidden ME, And made ME a polished shaft; In His quiver He has hidden ME.”
All of this is speaking of Jesus. It’s not that we should prepare for battle, but to rest in the one who has the victory.