"And the God of peace shall bruise Satan under your feet shortly. The grace of our Lord Jesus Christ be with you. Amen." - Romans 16:20 KJV

God is the “God of peace” because He made peace between humanity and Himself by putting on a body of flesh and blood so He could pay the price of our sins against Him, making peace between us, where before there was division from sin.

"And, having made peace through the blood of his cross, by him to reconcile all things unto himself [God reconciled everything to himself]; by him, I say, whether they be things in earth, or things in heaven.

“And you, that were sometime alienated and enemies in your mind by wicked works [This includes you who were once far away from God. You were his enemies, separated from him by your evil thoughts and actions], yet now hath he reconciled in the body of his flesh through death, to present you holy and unblameable and unreproveable in his sight [As a result, he has brought you into his own presence, and you are holy and blameless as you stand before him without a single fault]:

IF

“If ye continue in the faith grounded and settled [but you must continue to believe this truth and stand firmly in it], and be not moved away from the hope of the gospel, which ye have heard, and which was preached to every creature [all over the world] which is under heaven; whereof I Paul am made a minister;" - Colossians 1:20-23 KJV [brackets contain NLT translation]

We find peace and “the hope of the gospel” by Jesus’ death, burial, and resurrection, which we apply personally by repentance, baptism in Jesus name, and receiving the gift of God’s Spirit to live a new, holy life in Christ. This is what Paul preached. (Romans 6:1-13)

When Jesus made peace between us and Him on the cross, Jesus also conquered the devil.

"Forasmuch then as the children are partakers of flesh and blood, he also himself likewise took part of the same; that through death he might destroy him that had the power of death, that is, the devil; and deliver them who through fear of death were all their lifetime subject to bondage." - Hebrews 2:14-15 KJV

By the gospel - Jesus’ death, burial, and resurrection - Jesus abolished death and brought us life.

"But is now made manifest by the appearing of our Saviour Jesus Christ, who hath abolished death, and hath brought life and immortality to light through the gospel:" - 2 Timothy 1:10 KJV

When we obey the gospel, we step into life and immortality. (1 Corinthians 15:1-4, 54-55) We become conquerors.

We obey His gospel by being born again, born of water and of the Spirit. (John 3:5, Acts 2:38) We are born of water by water baptism in Jesus name. We are born of the Spirit when we are filled with His Spirit. (Acts 2:4, Acts 2:38)

"For whatsoever is born of God overcometh the world: and this is the victory that overcometh the world, even our faith." - 1 John 5:4 KJV

This is how satan is bruised under our feet.

Thayer’s Greek Lexicon translates “bruise satan under your feet” as, “to put Satan under foot and (as a conqueror) trample on him.”

"And they overcame [conquered] him by the blood of the Lamb, and by the word of their testimony; and they loved not their lives unto the death." - Revelation 12:11 KJV (the blood of the Lamb - HIS death, burial, and resurrection; the word of our testimony - OUR repentance, baptism in Jesus name, and gift of the Holy Ghost; and WE loved not our lives unto the death)

It is by the gospel that we stand.

We have prepared ourselves (the preparation) by obeying the gospel that brings us peace with God, applying His blood, His name Jesus, and His Holy Spirit to our life so that we may walk in victory with Him!

"And your feet shod with the preparation of the gospel of peace;" - Ephesians 6:15 KJV

Our feet shod with the gospel on our feet to “to put Satan under foot and (as a conqueror) trample on him.”