Twofold Efficacy*

since a death has occurred that redeems them from the transgressions committed under the first covenant.— Verse 15b
whom God put forward as a propitiation by his blood, to be received by faith. This was to show God’s righteousness, because in his divine forbearance he had passed over former sins.—Romans 3:25
And no longer shall each one teach his neighbor and each his brother, saying, ‘Know the LORD,’ for they shall all know me, from the least of them to the greatest, declares the LORD. For I will forgive their iniquity, and I will remember their sin no more.”—Jeremiah 31:34

Therefore he is the mediator of a new covenant, so that those who are called may receive the promised eternal inheritance,— Verse 15a
All this is from God, who through Christ reconciled us to himself and gave us the ministry of reconciliation;—2 Cor. 5:18
since God had provided something better for us, that apart from us they should not be made perfect.—Hebrews 11:40