The book of Hebrews opens with a clear summary making a clear distinction between how things were in the Old Testament and how things are now.

IN MANY separate revelations [each of which set forth a portion of the Truth] and in different ways God spoke of old to [our] forefathers in and by the prophets,

(Hebrews 1:1 AMPC)

God spoke in many ways in the Hebrew scriptures and this was God speaking. The Hebrew and Christian scriptures are one story all pointing to Jesus. Hebrews makes it very clear that while God spoke in the Old Testament, He is now uniquely speaking through His Son, who is clearly portrayed as the creator of all things.

[But] in the last of these days He has spoken to us in [the person of a] Son, Whom He appointed Heir and lawful Owner of all things, also by and through Whom He created the worlds and the reaches of space and the ages of time [He made, produced, built, operated, and arranged them in order].

(Hebrews 1:2 AMPC)

Hebrews echoes what we learned from Colossians about Christ’s identity. He is the “sole expression” of the Glory of God. The “perfect imprint and very image of [God’s] nature.”

He is the sole expression of the glory of God [the Light-being, the out-raying or radiance of the divine], and He is the perfect imprint and very image of [God's] nature, upholding and maintaining and guiding and propelling the universe by His mighty word of power. When He had by offering Himself accomplished our cleansing of sins and riddance of guilt, He sat down at the right hand of the divine Majesty on high,

(Hebrews 1:3 AMPC)

Certain individuals will knock on your door and try to tell you that Jesus was simply an angel and was not divine. Hebrews clearly debunks this lie by stating…

[Taking a place and rank by which] He Himself became as much superior to angels as the glorious Name (title) which He has inherited is different from and more excellent than theirs. For to which of the angels did [God] ever say, You are My Son, today I have begotten You [established You in an official Sonship relation, with kingly dignity]? And again, I will be to Him a Father, and He will be to Me a Son? [2Sa_7:14; Psa_2:7] Moreover, when He brings the firstborn Son again into the habitable world, He says, Let all the angels of God worship Him. Referring to the angels He says, [God] Who makes His angels winds and His ministering servants flames of fire; [Psa_104:4] But as to the Son, He says to Him, Your throne, O God, is forever and ever (to the ages of the ages), and the scepter of Your kingdom is a scepter of absolute righteousness (of justice and straightforwardness).

(Hebrews 1:4-8 AMPC)

The book of Hebrews places a bow on top of the incredible good news of the gospel. It clears up the confusion between the Old Covenant and the New Covenant and makes it clear that there is one God who is the author of both. The New Covenant simply replaces the old one because it is founded on better promises.

But as it now is, He [Christ] has acquired a [priestly] ministry which is as much superior and more excellent [than the old] as the covenant (the agreement) of which He is the Mediator (the Arbiter, Agent) is superior and more excellent, [because] it is enacted and rests upon more important (sublimer, higher, and nobler) promises. For if that first covenant had been without defect, there would have been no room for another one or an attempt to institute another one. However, He finds fault with them [showing its inadequacy] when He says, Behold, the days will come, says the Lord, when I will make and ratify a new covenant or agreement with the house of Israel and with the house of Judah.

(Hebrews 8:6-8 AMPC)

When God speaks of a new [covenant or agreement], He makes the first one obsolete (out of use). And what is obsolete (out of use and annulled because of age) is ripe for disappearance and to be dispensed with altogether.

(Hebrews 8:13 AMPC)