The blood of Christ, the most powerful weapon known to man.

Hebrews 9:14 (KJV)
How much more shall the blood of Christ, who through the eternal Spirit offered himself without spot to God, purge your conscience from dead works to serve the living God?

1 Peter 1:2 (KJV)
Elect according to the foreknowledge of God the Father, through sanctification of the Spirit, unto obedience and sprinkling of the blood of Jesus Christ: Grace unto you, and peace, be multiplied.

1 Peter 1:19 (KJV)
But with the precious blood of Christ, as of a lamb without blemish and without spot:

1 John 1:7 (KJV)
But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin.

Revelation 1:5 (KJV)
And from Jesus Christ, [who is] the faithful witness, [and] the first begotten of the dead, and the prince of the kings of the earth. Unto him that loved us, and washed us from our sins in his own blood,