I understand that many passages in scriptures have the power of sounding like a succinct rallying call, one that "cuts to the chase" and inspires people. However, you have to be very cautious about any particular scripture passage being your "motto," your "vow" (remember, Jesus most strongly warned against making any vows before God, ANY, no matter how worthy appearing) or having a passage be like your Cliff Notes (study summary) that gives you a "bottom line" for your spiritual life. The reason I am writing this is that I know many are fascinated with much of what Paul wrote, particularly Ephesians 6:10-18. (I'm not going to type it out because if you look it up yourself you really should read the whole short chapter 6 to have it in context).
Here's the problem. Whenever someone extracts one saying from the Bible, one is in danger of doing a transplant from the common understanding of the Bible authors and participants to the people of the time (which is what God intended) to reworking those quotes into a modern context.
First, a silly example for a smile. Suppose the Bible wrote about whales traveling in pods and how important it is to be like whales and travel in pods. Some modern people might think, "Whoa! The Bible is saying to always carry your IPods!" Yeah, I'm being silly but I want you to right up front understand what I mean about transplanting a valid scripture, but said in a certain understanding (that all observant Jews who were the early Christians, especially Paul, well understood about God and human life) into a modern cultural set of blinders that has trimmed away much of the richness of understanding of what they wrote about and lived within.
OK, so here is the problem with passages like Ephesians 6:10-18 taken out of context. Paul is writing about the need to "arm" one's self in spiritual combat, against the dark forces that rule earth. He is of course entirely correct. However, people of his time (and your own Christian and Jewish ancestors, and the Muslims too) would have understood this the way it was intended, and not the way moderns would view it. You see, moderns want "bad guys," especially "bad guy aliens" or "good guy superheroes." So many moderns see Eph 6:10-18 as validation that evil spirits walk the earth and manipulate people. Often moderns then view this as permission to shun or harm those they think are "on the other side." I mean, war has two sides, right? Combat is "against" someone, right?
OK, now, slam on the brakes. Who wrote this scripture? Where was the war at? How did Paul "know" there's a battle with dark spirits on one side against the good guys?
Well, here's the bombshell of understanding you have all forgotten. Paul was on "both sides." Paul was a Jew, a highly observant Jew, but he was also a Roman citizen. Ta da! When you forget that you have total misunderstanding of what Paul means as combat. Romans had enslaved the Jews. Paul "belonged" to both sides, as he was both a highly religious Jew (the slave) and a highly placed and favored Roman citizen being prepared for high secular office (the slave owner).
Remember, Jesus was crucified because he would not lead an armed rebellion (using his miracles as firepower) on behalf of the Jews against the Romans. Jesus was not crucified because he did not "wrestle....against principalities,...rulers of the darkness of this world, against spiritual wickedness in high places..." This is why Paul emphasizes WE WRESTLE NOT AGAINST FLESH AND BLOOD (Eph 6:12).
PAUL IS POUNDING IT INTO PEOPLE'S HEADS THAT NO FLESH AND BLOOD IS "THE ENEMY" BECAUSE DUE TO THAT ERROR JESUS WAS CRUCIFIED.
Notice too that when he writes about battling principalities, powers, rules of darkness and spiritual darkness and spiritual wickedness, he is speaking of battling SIN and FAITHLESSNESS. He is not speaking of battling either evil "spirits" in the way that people think of them today NOR is he speaking of declaring a group of people (like Romans, the hot enemy at the time) as being either demonic or flesh and blood enemies. No one is more qualified to role model and speak of that than PAUL, who was both well placed Roman citizen AND Jewish/now Christian oppressed.
Paul did not stop being Roman and renounce it for Christianity. Duh, read the scripture, as he invoked his Roman rights to trial throughout his ministry and died in Rome (via the means of death given to Romans, the sword, not crucifixion, like Peter suffered.) Paul did not say, "Hey, crucify me just like the Lord was." He took advantage of being Roman elite right to the end and there is absolutely nothing wrong with that, because he stayed alive longer to get the Gospel spread through his Evangelizing without being hypocritical.
So people well understood Paul's words in Ephesians and elsewhere as the battle being against the dark forces of SINS and UNBELIEF, not against evil "spirits" the way moderns think of them, or one group of humans against the other. Paul was against the bad spirituality (to use the modern terms) that is festering and spread in high places and principalities (places of authority, both secular and religious) via sin, hypocrisy and disbelief. Paul did not go to Rome to fight "against" them in "combat" to "defeat them." Paul went, like Peter, to Rome to defeat spiritual darkness (paganism and corruption) and CONVERT THEM. Spiritual combat aims at conversion, NOT fighting imaginary sources of power. No imagination is needed about the source of darkness if you read the scriptures and I don't mean just Satan. So I now need to explain the second part of this confusion, and let's use another example.
Let's use HIV/Aids disease as an example. No, I'm not causing grief by using this example but rather it is a perfect example to study. Sometime in the past century, scientists have a good idea but of course will never know exactly, the virus jumped from simian species like chimps onto a single human being. It then modified and changed as it adjusted to being in a human body and became the disease we are all too familiar with today.
So my first point is that Adam and Eve were the origin of the first sin, which was disobedience to God per temptation by Satan. Adam and Eve were tempted to "know as much as God," so to speak, so they ate the apple so they could know what evil was like. (There was nothing in the apple by the way. It was the sheer act of disobedience to the all good and loving God that opened their eyes to evil. I mean, if they had kicked God in the shins they would have also gotten the same info, the same 411, about good and evil because just being mean and disobedient to God is the initiation into sin and evil).
Now, once HIV/Aids jumped the one time to a human, it does not need to rejump from ape to human with each person who is infected, I mean, duh, right? Same with the flu or common cold. It does not need to be reinvented each time someone gets sick with cold or flu, right? Likewise is spiritual darkness. Satan only had to tempt Eve and her take it to Adam, and Satan can sit back in his lawn chair and watch. So when Satan is "at work" or there is spiritual darkness, it is not Satan running around reinventing temptation with each generation of each human being. Like Aids, it is out there and people spread it through contact with each other.
To misunderstand Ephesians 6 is like what happened with demonizing specific groups who suffer from HIV/Aids. Every type of person gets HIV/Aids, yet certain groups (like gay men) became demonized as the "causes." When one views Ephesians 6 in the wrong way, one is tempted to do likewise, to nominate yourself as the "clean" and "clear" "spirit warrior," and to thus thrust on the "other side" the "dark principalities" role and that is totally false to what Paul said AND LIVED.
Paul, following in Jesus' path, was condemning the unseen darkness of sin, disbelief, hypocrisy, spiritual slavery and corruption, while at the same time dampening down the tendencies to want flesh and blood warfare which he (as a persecutor) had also succumbed to, which is to kill the "enemy" in bodily form.
So Paul's inspiring words must be correctly understood as being against the dark invisible powers of sin, hypocrisy, corruption and disbelief, and not against invisible cartoon absurd imaginary "spirits" like so many modern dopes believe.
How to understand spiritual combat? Read about sin in the Bible. Start with these passages BY PAUL in 2 Timothy.
2:3 Thou therefore endure hardness, as a good soldier of Jesus Christ.
2:5 And if a man also strive for masteries, yet is he not crowned, except he strive lawfully.
2:9 Wherein I suffer trouble, as an evil-doer, even unto bonds; but the word of God is not bound. (Paul is saying he is treated like a bad guy, even put into prison, but despite what is done to him God's truth cannot be imprisoned).
2:15 Study to show thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth.
2:16 But shun profane and vain babblings: for they will increase unto more ungodliness.
2:24 And the servant of the Lord must not strive; but be gentle unto all men, apt to teach, patient.
2:25 In meekness instructing those that oppose themselves, if God peradventure will give them repentance to the acknowledging of the truth.
2:26 And that they may recover themselves out of the snare of the devil, who are taken captive by him at his will.
I put 2:26 in bold italics because that's the heart of it. Satan has set the original snare and that is the combat, to EVADE THAT SNARE. Satan has no need to run around inventing new snares and sending evil spirits to go after each person in each generation, duh. That is the combat, to recover themselves (pull themselves out of the snare that, like slavery, humans are born into through sin and continual temptation.)
3:13 But evil men and seducers shall wax worse and worse, deceiving and being deceived.
3:15 And that from a child thou hast known the holy scriptures, which are able to make thee wise unto salvation through faith which is in Christ Jesus.
(Notice that Paul is referring to scriptures still being needed, and that is OLD TESTAMENT scriptures, as New Testament didn't exist yet as Paul wrote this).
3:16 All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness.
3:17 That the man of God may be perfect, thoroughly furnished unto all good works.
What is the remedy, the "armor," the "combat" that Paul orders, to deal with the worsening evil of humans over time (3:13)? Scriptures, particularly the Old Testament for wisdom, and as the training path toward perfected humans into obedient goodness to God. PAUL ENDORSES NO OTHER APPROACH OR WAY.
4:2 Preach the word; be instant in season, out of season; reprove, rebuke, exhort with all long-suffering and doctrine.
You have to read page after page after page of what Paul truly instructs before one can enjoy, be inspired by, understand, and "follow" the much loved punch lines of Eph 6:10-18.
Here is further reading to understand the dark power is sin and disobedience, not imaginary sci fi aliens or evil spirits etc.
Separates from God Isa 59:2
Its wages: death Rom 6:23
Begets moral cowardice Josh 7:11-13
Hardens the heart Heb 3:13
Is very destructive Ps 34:21
Caused Israel's downfall 2 Chr 28:22-23
Causes misery Job 15:20
Brings reproach Prov 14:34
Enslaves the will 2 Tim 3:13
Excludes from heaven 1 Cor 6:9, 10
The forgiven warned "not to continue in sin" John 5:14, John 8:11, Rom 6:12
All have sinned Rom 3:23
All have gone astray Isa 53:6
To claim sinlessness is to lie Prov 20:9, 1 John 1:8-10
Jesus alone without sin 1 Pet 2:21-22
Through Satan's deception and subtlety Gen 3:1-13, 2 Cor 11:3
In the heart Matt 15:18, 19
Through lust of flesh James 1:13-15
Against the Holy Ghost Matt 12:31-32
Is destructive Prov 11:3
Is inexcusable John 15:22
Man obdurate in sin Amos 4:6-11