"You know that he was manifested to him to take away our sins ; And there is no sin in him ... For this is the Son of God manifested: that he may destroy the works of the devil." 1 John 3: 5, 8
Jesus, the Son of God, was "manifested", that is, made visible when he became man on earth. To whom was it manifested ? To the leaders of the people who did not want him; To the Jewish nation which did not recognize him as a messiah; Only a small group accepted it, among the crowds that followed him.
And we Christians ? It may happen that we do not recognize all the results of the coming of Jesus on earth. We are interested in the forgiveness of our sins and our salvation. It is a very limited perception of his work ! For there is much more in the two verses of the day: not only are our sins forgiven, but Jesus has taken them away by expiating them on the cross, and he has destroyed the works of the devil: he has rendered them inoperative, Their effects. However, one still awaits the manifestation of his final victory over Satan and evil in general.
The works of the devil include all the things he has introduced into the creation of God to defile him (the incitement to sin, the seduction of error, etc.). We were all slaves of sin, but believers are now freed from tyranny. Our sins are taken away, Satan is a vanquished enemy. Jesus Christ, by his redemptive act on the cross, "has washed us from our sins in his blood" (Rev. 1: 5) and by his death he rendered "powerless the one who had the power of death "That is, the devil "(Heb. 2:14).
The works of the devil will be definitely destroyed on the last day. Satan will be put out of harmony for eternity ; he will be cast into the lake of fire and brimstone, where the Beast and the false prophet are ; And they shall be tormented day and night for ever and ever" (Rev. 20:10).
During the ministry of Jesus on earth, an anticipation of this total destruction could be seen when it delivered the demoniacs. The demons themselves said : "Have you come before the time to torment us ?" (Matt 8:29) ; "Have you come to destroy us ?" (Luke 4:34).
All is victory in the work of Jesus and by grace we benefit !
Source (To pleasing the Lord)