If I am to give this talk I would use four main elements as defense against the attack, trickery and temptation of the Evil One:
• Word of God
• God and heavenly creatures
The fourth may raise your eyebrow because very often we are influenced by Protestants ways of doing it. But remember that they do not have the Sacraments and thus miss out on its efficacy.
Prayers are essential simply because Jesus said so. The reason why the disciple could not deliver demon was because they did not pray enough; and if they did they did not do it together with fasting.
You can invoke the precious blood of Jesus that was shed on the cross to cover you against the Evil One. That should be a powerful prayer because he was defeated on Calvary.
St Paul said to pray unceasingly. When you have a project or endeavor that is what you should do. If you are in a group, to activate 24 hours chain prayer. It is like barb wire where enemy cannot enter in.
The word of God is truth. Use that to deflect Satan’s lies. Jesus did that when he encountered the Devil when fasted in the desert.
Call upon the name of Jesus. Make use of the intercession of Mother Mary, angels and saints. Remember Mary was the woman who crushed the head of the serpent. Remind Satan of that when you ask Mary to intercede.
And Sacraments. The Eucharist and Confession are perfect foils to Evil’s attack because you are healthy by the nourishment of Jesus Christ and free from sins in Confession.
As for Ephesians 6, they are quite self-explanatory. St. Paul uses allegories but the main requirements are simple which are from verse 14-18.
The armors are:
Truth (belt) – Like a belt, truth will secure you.
Righteousness (breastplate) – When you are righteous and free from sin, it is like a breastplate – you will be protected in your vulnerable part – the heart.
Gospel (feet, where you stand on as your foundation) - Jesus is the cornerstone, and when He is your foundation, your house will not crumble.
Faith (shield) – Your faith will deflect the arrows of the Evil One which he aims at you. His trick and temptation will not hurt you.
Salvation (helmet) – We are certain of our salvation brought about by Jesus on the cross. It is like a helmet that protects our head. We will not die nor stumble.
Word of God (Sword of the Spirit) – God’s word is the sword of the Spirit. Like a sword it kills the attacker. Remember that God is bigger than Satan; the Holy Spirit gives us power to prevail but more so, to be conquerors.
And prayers and alertness. Pray whenever you think you are being attacked by the enemy or in vulnerable situation.
You may want to add community as a castle that protects you against the army of the enemy. The prayer of a group of holy people in your church or community is strong. It is like a strong wall which Satan unable to breach.
If you can expound on that, your forty minutes or so would be used up.