Ephesians 6:12-16
6:12
ὅτι    οὐκ
    ἐστιν
   ἡμῖν
   ἡ    πάλη
   πρὸς
   αἷμα
   καὶ
   σάρκα
   ἀλλὰ
For
we wrestle not
against
__
flesh and
blood 
but
πρὸς
    τὰς      ἀρχάς,
             πρὸς     τὰς      ἐξουσίας,
       πρὸς
        
against            principalities             against                  powers            against
τοὺς      κοσμοκράτορας
          τοῦ
     σκότους
        τούτου,
       πρὸς
     
           
the rulers      world                   of the darkness          of
this              against
τὰ
πνευματικὰ     τῆς
     πονηρίας
     ἐν     τοῖς        ἐπουρανίοις.
spiritual wickedness in high places
Principalities,
Powers, etc. have already been mentioned as neutral in: 
A portion
(1/3, Rev. 12:4)) rebelled and are now hostile to God 
They have
been disarmed in Colossians 2:15 on the cross.
Disarmed
powers are no threat to the saved people who are covered with the panoply of
God.
But, the
problem for the believer is that they may not have put that armor on.
The
believer has been told to "put off
the old self" and "put on
the new self, created to be like God in true righteousness and holiness"
in Eph.       4:22-24
Believers
can even give Satan and his principalities room in their lives: "Do not   give the devil a foothold." (Eph.4:27)
Classes of
Evil Forces:
People who
disobey are under their power and authority (Eph. 2:2)
6:13
διὰ
τοῦτο
ἀναλάβετε
   τὴν
πανοπλίαν
 τοῦ
θεοῦ,
ἵνα
δυνηθῆτε
ἀντιστῆναι
ἐν 
Wherefore
__
take
unto you the whole armour of God that
ye
may be able to withstand in
τῇ
ἡμέρα
τῇ
πονηρᾷ
καὶ
ἅπαντα
κατεργασάμενοι
στῆναι.
the evil day and having done all to stand
The panoply is available, but we must put it on.
"Put on" - "ἀναλάβετε" is aorist imperative active 
The Roman
soldier was a man who could be counted on.
"Having
Done All" means "having accomplished all that your duty
requires"
The Roman
soldier was to stand his ground and not give up.
Paul says,
when you have done your full duty of standing your ground, then you 
            still must stand. 
We live in
an evil age, so the day of evil would be a particular time when that evil manifests
itself in a moment in our life.
6:14
στῆτε
οὖν
περιζωσάμενοι
τὴν   ὀσφὺν
   ὑμῶν
   ἐν
   ἀληθείᾳ      καὶ
Stand     therefore
having       your     loins 
girt about    with      truth           and
ἐνδυσάμενοι
   τὸν     θώρακα     τῆς
    δικαιοσύνης
having on the breastplate of righteousness
Each piece of armor is a
divine characteristic or gift.
This armor, of divine
character is the way you stand.
1 Thes. 5:8
These are ethical qualities
These are not:
1)     Belt of
Truth - Isaiah 11:5
"righteousness shall be the girdle of his waist, and faithfulness (LXX
"truth") the girdle of his loins"
2)     Breastplate
of righteousness - Isaiah 59:11
righteousness is the breastplate. 
3)     Feet fitted
with the readiness that comes from
the Gospel of peace - The feet are what you will be using to stand. Isaiah 52:7
and Romans 10:15. The "readiness" refers to the person whose feet are
prepared to understand and proclaim the gospel. We must know and communicate
the gospel that enables us to stand.
4)     Shield of
Faith - fire tipped darts - is this
faith in God or faithfulness to God. The answer is in 1 Peter 5:8-9. Here Satan
is resisted by being firm in your faith. This is flint like resolution and
commitment to what you believe.
5)     Helmet of
Salvation- Isaiah 59:17 Yahweh wears
this and gains the victory. 1 Thessalonians 5:8 mentions the hope of salvation.
6)     Sword of
the Spirit, Word of God - Isaiah
11:4; Revel. 19:15; Deut 8:3. This is the Word of God, spoken by the Spirit and
heard by us empowered by the Spirit
7)     Prayer