“… and since we have a great priest [Jesus Christ] over the house of God, let us draw near to God with a sincere heart in full assurance of faith, having our hearts sprinkled [with the blood of Christ] to cleanse us from a guilty conscience and having our bodies washed with pure water [the Holy Spirit at the new birth]. Let us hold unswervingly to the hope we profess, for He who promised [both the Father and the Son] is faithful.
Hebrews 10:21-24

“But Christ came as High Priest of the good things to come, with the greater and more perfect tabernacle not made with hands, that is, not of this creation. Not with the blood of goats and calves, but with His own blood He entered the Most Holy Place once for all, having obtained eternal redemption. For if the blood of bulls and goats and the ashes of a heifer, sprinkling the unclean, sanctifies for the purifying of the flesh, how much more shall the blood of Christ, who through the eternal Spirit offered Himself without spot to God, cleanse your conscience from dead works to serve the living God? Hebrews 9:11-14

The Holy Spirit also testifies to us about this. First he says:
"This is the covenant I will make with them
after that time, says the Lord.
I will put my laws in their hearts,
and I will write them on their minds." Then he adds:
"Their sins and lawless acts
I will remember no more."

And where these have been forgiven, there is no longer any sacrifice for sin. Hebrews 10:15-18