Satan is known as the Prosecutor. We understand this, as he accuses the brethren.

Revelation 12:10 And I heard a loud voice saying in heaven, Now is come salvation, and strength, and the kingdom of our God, and the power of his Christ: for the accuser of our brethren is cast down, which accused them before our God day and night.

When Jesus died for our sins, Satan lost his power. Jesus took from him the keys of hell and death.

Revelation 1:18 I am he that liveth, and was dead; and, behold, I am alive for evermore, Amen; and have the keys of hell and of death.

Hebrews 2:14 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;

Colossians 2:15 And having spoiled principalities and powers, he made a shew of them openly, triumphing over them in it.

Satan opposes the gospel which brings the mercy of God by the blood of Jesus.

2 Timothy 1:10 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:

We receive life through the gospel when we follow what Peter preached on the day of Pentecost.

Acts 2:38 Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost.

Jesus appeared to Paul and made him a minister and witness and sent him to the Jews and Gentiles,

Acts 26:18 To open their eyes, and to turn them from darkness to light, and from the power of Satan unto God, that they may receive forgiveness of sins, and inheritance among them which are sanctified by faith that is in me.

By the gospel, we have been brought out of the darkness of judgment into the light of God’s mercy.

Ephesians 5:6-8 Let no man deceive you with vain words: for because of these things cometh the wrath of God upon the children of disobedience. Be not ye therefore partakers with them. For ye were sometimes darkness, but now [are ye] light in the Lord: walk as children of light:

1 Peter 2:8-10 And a stone of stumbling, and a rock of offence, even to them which stumble at the word, being disobedient: whereunto also they were appointed. But ye are a chosen generation, a royal priesthood, an holy nation, a peculiar people; that ye should shew forth the praises of him who hath called you out of darkness into his marvellous light: Which in time past were not a people, but are now the people of God: which had not obtained mercy, but now have obtained mercy.

We no longer are subject to Satan’s accusations. When we were baptized in Jesus name, all our sins were washed away. The Prosecutor has nothing against us anymore!

Jesus promises that when we are baptized in his name he will give us his Spirit, the Holy Ghost. The Holy Ghost is not only power to resist sin, the Holy Ghost also acts as our Defense Attorney. Defense Attorney (“counsel for defense”) is a meaning of the Greek word translated to “Comforter”!

John 14:16-18 And I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever; Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth with you, and shall be in you. I will not leave you comfortless: I will come to you.

John 16:7-11 Nevertheless I tell you the truth; It is expedient for you that I go away: for if I go not away, the Comforter will not come unto you; but if I depart, I will send him unto you. And when he is come, he will reprove {convict} the world of sin, and of righteousness, and of judgment: Of sin, because they believe not on me; Of righteousness, because I go to my Father, and ye see me no more; Of judgment, because the prince of this world is judged.

Jesus, as our defense attorney, "pleads the blood" reminding Satan he has nothing to accuse us with!