Hebrews 1 only makes sense if Jesus is God's only begotten son. Hebrews 1 (WEB):
1) God, having in the past spoken to the fathers through the prophets at many times and in various ways,
Were the prophets God? No.
2) has at the end of these days spoken to us by his Son, whom he appointed heir of all things, through whom also he made the worlds.
Was his son God? Likewise no. God made the universe through His son - he had Jesus perform the creation according to His design, but it was still God's creation. However, after God resurrected Jesus to life again, God has blessed Jesus with an immortal nature and He has given His creation to Jesus as an inheritance, from father to son.
3) His Son is the radiance of his glory, the very image of his substance, and upholding all things by the word of his power, who, when he had by himself purified us of our sins, sat down on the right hand of the Majesty on high;
Jesus now has the same divine nature as God (previously he was not immortal, which is why he was able to die for mankind). He is now sat down at God's right hand (he is not God, the Majesty on high, but he is God's 'right-hand man').
4) having become so much better than the angels, as he has inherited a more excellent name than they have.
Jesus has now become so much better than the angels (he was better before, for he created them, but he is now much better, having become immortal, and given by God all authority and power over God's creation). Regarding Jesus' more excellent name, Philippians 2:9-11 says "Therefore God also highly exalted him, and gave to him the name which is above every name; that at the name of Jesus every knee should bow, of those in heaven, those on earth, and those under the earth, and that every tongue should confess that Jesus Christ is Lord, to the glory of God the Father.
5) For to which of the angels did he say at any time, “You are my Son. Today I have become your father?” and again, “I will be to him a Father, and he will be to me a Son?”
Only Jesus is God's only-begotten son. Jesus was begotten as God's firstborn son of his new creation (of which we are also begotten at our baptism) at his baptism, when as recorded in Matthew 3:17, Behold, a voice out of the heavens said, “This is my beloved Son, with whom I am well pleased.”
6) When he again brings in the firstborn into the world he says, “Let all the angels of God worship him.”
Jesus was the firstborn of all God's creation (Colossians 1:15). It is now right, according to God, for all angels and all men to worship Jesus, as well as worshiping God.
7) Of the angels he says, “Who makes his angels winds, and his servants a flame of fire.”
8) But of the Son he says, “Your throne, O God, is forever and ever. The scepter of uprightness is the scepter of your Kingdom.
9) You have loved righteousness, and hated iniquity; therefore God, your God, has anointed you with the oil of gladness above your fellows.”
God refers to Jesus as a god - 'god' means a mighty one. Jesus is truly a mighty one, but God is still his god. God has annointed Jesus with more gladness (exultation, exceeding triumphant joy) than anyone else.
10) And, “You, Lord, in the beginning, laid the foundation of the earth. The heavens are the works of your hands.
God confirms again that He had Jesus create the universe.
11) They will perish, but you continue. They all will grow old like a garment does.
The universe will decay over time, but Jesus won't.
12) You will roll them up like a mantle, and they will be changed; but you are the same. Your years will not fail.”
For Jesus is now immortal, like God is.
13) But which of the angels has he told at any time, “Sit at my right hand, until I make your enemies the footstool of your feet?”
Only Jesus sits at God's right hand, while God overcomes Jesus' enemies (alhough He may use Jesus to overcome them).
14) Aren’t they all serving spirits, sent out to do service for the sake of those who will inherit salvation?
1 John 4:9 (WEB):
9) By this God’s love was revealed in us, that
God has sent his one and only Son into the world that we might live through him.
10) In this is love, not that we loved God, but that
he loved us, and sent his Son as the atoning sacrifice for our sins.
11) Beloved, if God loved us in this way, we also ought to love one another.
12) No one has seen God at any time. If we love one another, God remains in us, and his love has been perfected in us.
13) By this we know that we remain in him and he in us, because he has given us of his Spirit.
14) We have seen and testify that
the Father has sent the Son as the Savior of the world.
15)
Whoever confesses that Jesus is the Son of God, God remains in him, and he in God.