Before launching into the specifics of the whole armour of God (v.11) Paul first lays out the main purpose, the big point, of spiritual warfare and all that the Lord provides for His people:
“For this reason, take up the full armor of God so that you may be able to stand your ground on the evil day, and having done everything, to stand.”
(Ephesians 6.13, NET)
Because of the reality of spiritual warfare (for this reason, cf. vv.11-12) we need help. Without help we would, simply, fail. Because spiritual warfare is an absolute reality in the lives of those following the Lord Jesus (vv.11-12, cf. 1 Peter 5.8) and yet something to be conquered, not cowered before, help is at hand. The spiritual resources that God provides, and that Paul will detail in the remainder of this passage, are there expressly to allow you to be able to stand your ground on the evil day.
David Guzik writes
“God has given His people a call, a mission, a course to fulfill. Satan will do his best to stop it. When he attacks and intimidates, we are to stand. It is plain that this is Paul’s emphasis in Ephesians 6:11 and 6:13. We do the Lord’s work and stand against every hint of spiritual opposition.”
There will be pushback when you step out in faith and begin to truly live a life of love in the Lord Jesus. Spiritual warfare is not something we call when the toast is burnt, we’re out of coffee, or there is traffic on the highway, but when you are doing the Lord’s work, living the life He died to secure for you, there will undoubtedly be pushback.
The encouragement for you and for me is that we have been given the very tools we need to overcome the trials and tribulations that are par-for-the-course for the Christian (1 Peter 1.7-9). Don’t take the battle on yourself, in your own power and might, but take up the full armour of God: the battle belongs to the Lord. You can stand because of what you hold by grace and through faith.