Why does the death and resurrection of Christ make Him the Firstborn and First Begotten? Let's examine.
SON OF GOD: HAD CHRIST ALWAYS BEEN THE SON OF GOD IN ETERNITY PAST?
Ge 1:26 And God said, Let US make man in our image, after OUR likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth.
Joh 1:1 In the beginning was the Word, and the Word was with God, and THE WORD WAS GOD.
Joh 1:14 And THE WORD WAS MADE FLESH, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth.
Col 1:17 And HE IS BEFORE ALL THINGS, and by him all things consist.
Ga 4:6 And because ye are sons, God hath sent forth the SPIRIT OF HIS SON into your hearts, crying, Abba, Father.
Joh 17:5 And now, O Father, glorify thou me with thine own self with the GLORY WHICH I HAD WITH THEE BEFORE THE WORLD WAS.
Joh 8:58 Jesus said unto them, Verily, verily, I say unto you, BEFORE ABRAHAM WAS I AM.
Joh 17:21 That they all may be one; AS THOU, FATHER, [art] IN ME, AND I IN THEE, that they also may be one in us: that the world may believe that thou hast sent me.
Joh 17:22 And the glory which thou gavest me I have given them; that they may be one, EVEN AS WE ARE ONE:
Joh 10:30 I AND [my] FATHER ARE ONE.
SIN: THE SEPARATION
Isa 59:2 But your *iniquities* have SEPARATED between you and your God, and your sins have hid [his] face from you, that he will not hear.
Jer 5:25 Your iniquities have turned away these [things], and *your sins* have WITHHOLDEN GOOD  from you.
De 31:18 And I will surely HIDE MY FACE in that day for all the evils which they shall have wrought, in that they are turned *unto other gods*.
Eze 39:23 And the heathen shall know that the house of Israel went into captivity for their iniquity: because *they trespassed against me*, therefore HID I MY FACE FROM THEM, and gave them into the hand of their enemies: so fell they all by the sword.
Eze 39:24 According to their uncleanness and according to *their transgressions* have I done unto them, and HID MY FACE FROM THEM.
Pr 15:29 The LORD [is] FAR FROM *THE WICKED*: but he heareth the prayer of the righteous.
FIRST BEGOTTEN (FIRST BORN): CHRIST, MADE RECONCILIATION FOR THE ELECT THROUGH THE RESURRECTION
Re 22:13 I am Alpha and Omega, the beginning and the end, THE FIRST and the LAST.
Joh 11:25 Jesus said unto her, I AM THE RESURRECTION, and the life: he that believeth in me, though he were dead, yet shall he live:
Ac 26:23 That Christ should suffer,  that he should be the FIRST THAT SHOULD RISE FROM THE DEAD, and should shew light unto the people, and to the Gentiles.
Ro 1:4 And declared [to be] the SON OF GOD with power, according to the spirit of holiness, BY THE RESURRECTION from the dead:
Re 1:5 And from Jesus Christ,  the faithful witness,  the FIRST BEGOTTEN OF THE DEAD, and the prince of the kings of the earth. Unto him that loved us, and washed us from our sins in his own blood,
1Pe 1:3 Blessed [be] the God and Father of our Lord Jesus Christ, which according to his abundant mercy hath BEGOTTEN US AGAIN unto a lively hope by the RESURRECTION OF JESUS CHRIST from the dead,
Ac 13:33 God hath fulfilled the same UNTO US their children, in that he hath RAISED UP JESUS AGAIN; as it is also written in the second psalm, Thou art MY SON, this day have I BEGOTTEN THEE.
Ps 2:7 I will declare the decree: the LORD hath said unto me, Thou [art] MY SON; this day have I BEGOTTEN THEE.
Heb 1:5 For unto which of the angels said he at any time, Thou art MY SON, this day have I BEGOTTEN THEE? And again, I will be to him a Father, and he shall be to me a Son?
Heb 1:6 And again, when he bringeth in the FIRSTBEGOTTEN into the world, he saith, And let all the *angels* of God worship him.
Heb 2:10 For it became him, for whom [are] all things, and by whom [are] all things, in bringing MANY SONS unto glory, to make the captain of their salvation perfect through sufferings.
Heb 2:17 Wherefore in all things it behoved him to be made like unto [his] *brethren*, that he might be a merciful and faithful high priest in things [pertaining] to God, to make RECONCILIATION for the sins of the people.
Eph 2:16 And that he might RECONCILE both unto God IN ONE BODY BY THE CROSS, having slain the enmity thereby:
Lu 15:24 For this MY SON WAS DEAD, and is ALIVE AGAIN; he was lost, and is found. And they began to be merry.
Lu 20:36 Neither can they die any more: for they are equal unto the angels; and are the children of God, being the CHILDREN OF THE RESURRECTION.
Ro 6:5 For if we have been PLANTED TOGETHER in the likeness of his death, we shall be also [in the likeness] OF [his] RESURRECTION:
Php 3:10 That I may know him, and the POWER OF HIS RESURRECTION, and the fellowship of his sufferings, being made conformable unto his death;
Joh 1:14 And the Word was made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only BEGOTTEN OF THE FATHER,) full of grace and truth.
Joh 1:18 No man hath seen God at any time; the ONLY BEGOTTEN SON, which is in the bosom of the Father, he hath declared [him].
Joh 3:16 For God so loved the world, that he gave his ONLY BEGOTTEN SON, that whosoever believeth in him should not perish, but have everlasting life.
1Jo 4:9 In this was manifested the love of God toward us, because that God sent his ONLY BEGOTTEN SON into the world, that we might live through him.
To be the Firstborn or First Begotten from the dead appears to be the message of salvation. Christ is the FIRST as well as the RESURRECTION. His ability to successfully undergo the atonement made Him the FIRST of many SONS to follow because it was then possible for the Elect to be reconciled to God.