The New Covenant

Hebrews 10:14-18 (New American Standard Bible)
14For by one offering He has perfected for all time those who are sanctified.
15And the Holy Spirit also testifies to us; for after saying,
16"THIS IS THE COVENANT THAT I WILL MAKE WITH THEM
AFTER THOSE DAYS, SAYS THE LORD:
I WILL PUT MY LAWS UPON THEIR HEART,
AND ON THEIR MIND I WILL WRITE THEM,"
He then says,
17"AND THEIR SINS AND THEIR LAWLESS DEEDS
I WILL REMEMBER NO MORE."
18Now where there is forgiveness of these things, there is no longer any offering for sin.

It is interesting that in this passage God not only promises that He will forget our sins and remove them, but that He will replace them. God promises that through the Spirit, we will have His righteousness engrained in our hearts. We are eternally forgiven of our sins, but there is still the responsibility to live for God. This new covenant is a repeated theme throughout the letter to the Hebrews. The message is that the old Hebrew system of sacrifices is gone, and instead Jesus' single sacrifice has sealed us for eternity.