How do we know the New Covenant is better?

The New Covenant is termed 'better' in Hebrews because it supersedes the Old Covenant established at Sinai, characterized by laws demanding strict adherence. In contrast, the New Covenant emphasizes grace through faith in Christ, who perfectly obeyed the law and became the ultimate sacrifice for sin. It is unilaterally given by God, unlike the conditional terms of the Old Covenant, and is also sealed by Christ's blood. The promises of the New Covenant highlight God’s faithfulness and assurance of salvation, resting firmly in His character and purpose, which cannot fail.