What does the Bible say about entering the holy of holies?

Hebrews 10:19-20 explains that believers have boldness to enter into the holiest, the very presence of God, through the blood of Jesus. This access is made possible because Christ's sacrifice has completed the need for any further offerings for sin, thus allowing believers to come with fearless assurance. The text emphasizes the radical change from the Old Testament practice where only the high priest could enter the holy of holies once a year, underscoring the total access believers now have to God through Christ’s atoning work.